by:. introduction. what is a control valve. the available configurations and sizes. the construction...

Introduction.

What is a control valve.

The available configurations and sizes.

The construction of a basic control valve.

The different component specifications.

The operating principle.

Understanding the two types of control systems.

Factors to consider when selecting a control valve.

Pilot Valves.Valve accessories -

Questions relating to hydraulic relays.

Understanding electric solenoid valves.

Other devices and fittings.

A few commonly used valve examples - Open / Close Valves.

Pressure Regulating Valves.

A control valve is a semi - automatic directional device which controls flow and or pressure within a water supply network.

Control valves are generally set to the required operating parameters on installation and thereafter require no further operator intervention.

Threaded connections - 40mm, 50mm, 65mm, 80/65/80mm & 80mm

Flanged connections - 80mm, 100mm, 150mm & 200/150mm

Inline Valves

Threaded connections - 50mm, 65mm, 80/65/80mm & 80mm

Angle Valves

Gator control valves are constructed from 5 main components. These are:

The Bonnet

The Spring

The Spring Retainer DiskThe Diaphragm

The Body

The Bonnet.

Materials - Manufactured from grade 14 cast iron.

Coatings – Fusion bonded epoxy powder coated. External Coating – UV stabilized polyester coated. Internal Coating – Chemically stabilized epoxy coating. Other coating options are available on request.

Control System Ports - Number of control ports - 2 Thread type - BSP or NPT. Port sizes - On the 50, 65, 80/65/80 &150 valves, both ports are 1/4"

On the 80 & 100 valves the center top port is 1/2" and the angled side port is 1/4"

Markings - Directional indication arrow, valve name & valve size in metric format.

Optional Devices - A mechanical throttle can be fitted to the valves bonnet allowing the valves pressure to be adjusted. The mechanical throttle allows for pressure control on the valve in systems where the upstream pressure before the valve is always the same. A valve fitted with a mechanical throttle is not a modulating valve.

A valve fitted with mechanical throttle

The Spring

Materials - Manufactured from Stainless Steel.

Finish - Ground on bottom end to accommodate spring retainer disk.

The Spring Retainer Disk

Materials - Manufactured from Glass Reinforced Nylon.

Finish - Fitted with locator hole to locate the diaphragm.

The Bolts, Nuts & Washers

Materials - Manufactured from 304 grade stainless steel.

Thread Specifications - Metric standards.

General - Bolts are of the set screw type. Nuts are of the Nylok type and washers are plain flat washers.

The Diaphragm

Materials - Manufactured from SMR 20 Natural Rubber and center reinforced with RFL treated Woven Nylon Cloth.

Other materials, such as, EPDM, Nitrile and Neoprene are available on request.

Note !!! - Gator valve diaphragms used in clean, dirty, untreated or treated effluent water are guaranteed for one year.

Flow Convergence Ribs – DN80, DN100 & DN150 diaphragms are moulded with Flow Convergence Ribs to allow smoother operation of the valve at lower flows.

Regulation is also possible at lower than normal flows without vibration occuring in the valve.

The Body

Materials - Manufactured from grade 14 cast iron.

Control System Ports - Number of control ports - 2 1 upstream and 1 downstream

Thread type - BSP or NPT. Port sizes - All ports are 1/4"

End Connections - Flanged options are: BS10 Table D/E/F, ISO PN10/16/25, ANSI 125/150/ 250/300 & JIS 10/20. Threaded options are: BSP or NPT.

Markings - Valve name and valve size (in metric format).

General - The Gator valve body is symmetrical and can therefore be used in either direction. This however does not apply once the control network has been plumbed onto the valve. The valve should be installed in accordance with the directional arrow on the bonnet.

Coatings – Fusion bonded epoxy powder coated. External Coating – UV stabilized polyester coated. Internal Coating – Chemically stabilized epoxy coating. Other coating options are available on request.

Single Chamber

OutletInlet

Weir

Gator valves are simple single chamber inline or angle control

valves which operate using the available pipeline pressure

or an external pressure supply of air or water, provided

this pressure is equal to or greater than the pressure of

the pipeline, in which the control valve is installed.

To open the valve.To open the valve, the water or air trapped within the

upper chamber is released into atmosphere or into the

downstream of the valve, into the pipeline. The diaphragm

is forced upwards by the pressure within the pipeline

allowing the valve to open.

Inlet Outlet

Upper Chamber

To close the valve.

Inlet Outlet

Upper Chamber

To close the valve, water or air pressure is induced

into the upper chamber forcing the diaphragm to close

against the weir within the valve and thereby stopping the

flow of the liquid within the pipeline.

Weir

The hydraulic closing action.

b) The spring aids the valve to close specifically when friction loss is at a minimum. When friction loss across the valve is sufficient, the spring plays little or no role.

Although the surface areas above and beneath the diaphragm are equal, the valve will close when water (which is at equal pressure within the pipeline upstream of the valve) is induced into the upper chamber due to the following reasons:

a) Under closing operation, the hydraulic energy above the diaphragm is greater than beneath the diaphragm due to the friction loss generated across the valve. For example if the upstream operating pressure within the pipeline is 5 Bar and the valve has a friction loss of 0.3 Bar, the pressure beneath the diaphragm would vary between 5 (upstream) and 4.7 Bar (downstream) while the pressure on the full upper surface of the diaphragm is 5 Bar. The more the valve closes the higher the pressure differential between the top of the diaphragm and below the diaphragm, thus causing the valve to close securely.

5 Bar 4.6 Bar 5 Bar 3 Bar 5 Bar 0 Bar

5 4 34.9

4.8

4.7

Fully Open Valve Closing Valve Fully Closed Valve

00

55 55

5 5

The regulating mode.

Inlet Outlet

Upper Chamber

By incorporating other control mechanisms, the valve

can be adapted to regulate flow without being fully closed

or fully open. The valves diaphragm is the only moving part

and is assisted to close under all pressures with the aid of

a spring.

The three way system.

There are two control systems utilized by single chamber valves. These are, the three way control and systemand the two way control system.

Definition - A selector valve, activated manually, and/or electrically, by upstream media pressure or by an external media pressure.

The valve generally has three positions of operation.

Position 1 - When pressure is induced into the control chamber the valve will close.

The Closed Valve

1 Selector Valve

The Open Valve

2 Selector Valve

The Regulating Valve

3 Selector Valve

Position 2 - When pressure is relieved from the valve chamber into atmosphere, the valve will open.

Position 3 - When the flow path from the selector valve to the control chamber is closed, the position of the diaphragm is set. This situation is not applicable to OPEN/CLOSE control valves but is required for modulating valves.

Use a 3 Way Control System When :

OPEN - CLOSE valves are required.

Low pressure differential is required.

The controlled media is a very dirty or abrasive liquid.

The control media is different from the controlled media (within the pipeline) e.g. Pneumatic control of water network.

Do NOT use a 3 Way Control System When :

Extreme fluctuations in network operating conditions areanticipated.

No Flow (shut off) situations are expected.


The Closed Valve

1 Selector Valve

The Open Valve

2 Selector Valve


3 Selector Valve

Definition - A control configuration of two flow restricting devices working together to control the valve.

Flow restrictor "a" is a fixed passage restrictor fitted to the upstream of the control network (Normally a needle valve is used for this task).

Flow restrictor "b" is either an OPEN - CLOSE device or modulating pilot valve which is fitted to the downstream control network of the valve.When this device is fully open the passage within the device should be larger than the passage of restrictor "a"

The control valves operation is effected by the downstream restrictor device "b" in the following ways:

Position 1 - When device "b" is fully closed, the valve will close, due to the fact that the control media cannot vent into the downstream. In this position, the surface area above the diaphragm is ± 2 x greater than the surface area beneath the diaphragm, thus causing the valve to close.

The Closed Valve

1 “a” “b”

The Open Valve

2 “a” “b”


3 “a” “b”

The two way system.

Position 2 - When device "b" is fully open, the valve will open to a point where the pressure in the control chamber is equal to the pressure in the downstream of the control valve. As the volume of control media which can pass through restrictor "a" is less than what can pass through restrictor "b", the pressure above the diaphragm is less than the pressure beneath the diaphragm, causing the valve to open.

Position 3 - When the flow passage of device "b" is modulated, the relationship between device "a" and "b" will cause the valve to respond to this modulation. The valve will position itself to the pre-set pressure of the pilot valve "b" On pressure change in the system, device "b" will alter it's passage opening causing the control valve to respond as well.

The Closed Valve

1 “a” “b”

The Open Valve

2 “a” “b”


3 “a” “b”

The two way system.


Sensitive regulation at low pressure is required.

A pressure differential is required at all operating conditions.

Little pressure reduction is required.

Simplicity of control and setting of the valve and systemare essential.

NO flow (shut off) regulation is required.


When full opening of the control valve is required for absoluteminimum pressure loss under certain operating conditions.

When the control media is not the same as the controlledmedia in the pipeline.

When the controlled media is very dirty or abrasive.

Note !!! The setting of the needle valve "a" can have an important effect on the pressure loss across the control valve. The smaller the passage in this device, the less the friction loss across the valve, however, the slower the response time of the control valve. Slow response time can lead to over pressure within the control system.

Pressures.

Temperatures.

Media

Velocities

Pressure Loss.

Cavitation.

Pressure Reduction.

Open Discharge Systems.

Three way or two way operation ?

Pressures.

The Minimum Operating Pressure.

The Maximum Operating Pressure.

The minimum pressure required to open all Gator valves is 7 meters.

Check to ensure that the system upstream pressure is not below 7 meters as this can cause the valve not to open or to onlypartially open.

A partially open valve will cause higher than normal friction loss which could result in poor and inaccurate valve performance.

All Gator valves are rated to operate at a maximum shut off pressure of 160 meters (16 Bar).

Although tests conducted on Gator valve diaphragms have confirmed that all the diaphragms can handle up to 250 meters(25 Bar) of pressure, valves should not be designed for operating conditions above 16 Bar.

1 2 30 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20

No Operation Recommended Accepted Not Recommended

1 2 30 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20

Operating Pressure in Bar

Minimum Operating Pressure 0.7 Bar Maximum Operating Pressure 16 Bar

Operating Temperatures.

The Maximum Operating Temperature.

The maximum operating temperature for Gator valves fitted with standard SMR 20 natural rubber diaphragms is 70° Celsius.

Consult with your supplier for valves which are to be used at higher operating temperatures.

Max 70° CMax 70° C

MediaThe media with which a Gator valve is to be controlled.

This can be defined as the media within the pipeline which is controlled by a Gator valve.

Gator valves are suitable for controlling slurries, untreated sewage water, water with a high sand content as well as most normal media types which are generally controlled by such valves.

This is possible due to the design of the valve which has no shafts, bearings, seals or discs.

This can be defined as the media which is used to control the valve.

This media is generally the same as that which is in the pipeline into which the control valve is installed.It is however possible to use an external media. This can be air or clean water and should be used if the media

within the pipeline is dirty or abrasive.

The media to be controlled by a Gator valve.

Velocities.Gator control valves may be used at very high velocities due to the weir shape of the valves body, which is almost turbulence free.

The valve may be operated in the fully open position at 7-8 m/sec. velocity without noise, shuddering or cavitational damage.

Velocity Chart50 mm 65 mm 80 mm 100 mm 150 mm

0

30 60 90 120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

630

00.5

11.5

22.5

33.5

44.5

55.5

66.5

77.5

88.5

99.510

Flow Rate (m³/hr)

Velocity (m/sec)

0.5 to 5 m/sec. Highly Recommended

5 to 8 m/sec. Accepted

8 to 15 m/sec. is Accepted for very shortperiods of time (up to 30 sec.) otherwisenot recommended at all.

0 to 0.5 m/sec Not Recommended

Pressure Loss.

Due the valves construction, the water passes through the valve with minimal direction change, therefore keeping head lossto a minimum.

Headloss ChartScrewed Valves

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 8505

101520253035404550

Flow Rate (m³/hr)

Headloss (Kpa)50mm 65mm 80/65/80 80mm

Most common zone of operation

In certain applications (such as pressure reducing operations), it t is often advantages to select a valve that has a slightly higher head loss in order to obtain a more positive and direct response from the control valve.

Note !!! Head loss in valves fitted with two way control systems is higher than valves fitted with 3 way control systems.

Cavitation.This is the term used for the formation and subsequent collapse of vapour bubbles in the regions of low pressure within a flowing liquid.

Cavitation is caused by the liquid in the system passing through the throttling section of the valve, it's velocity increases and it's pressure decreases below the liquid's vapour pressure, and vapour bubbles are formed.

Throttling Section Vapour Bubbles

Damage Zone

Downstream of the valves throttling section, flow suddenly expands, it's velocity decreases and static pressure recovers. When recovered pressure increases above vapour pressure, it causes a violent collapse of the vapour bubbles which result in intense heat and shock waves which will eventually destroy any material they contact.

If the downstream pressure is less than vapour pressure, (e.g. atmosphere) bubbles will remain in vapour state and cavitation is prevented.

Cavitation in Gator valves can occur when the pressure reduction ratio between the upstream and the downstream exceeds a 3:1 ratio. Cavitation damage can be identified by : Noise and vibration in the valve and ajoining pipework, an unexplained rise in headloss and erosion of the valve and ajoining pipework.

Pressure Reduction.

Where the pressure reduction ratio across the valve exceeds 3:1 or where cavitation damage can be caused, it is recommendedto implement one of the following solutions.

Solution 1 - Install two valves in series, setting each valve to create a pressure reduction within the 3:1 reduction ratio.

Solution 2 - Install an orifice plate in series with a reduction valve on the upstream of the pipeline. This solution is limited tosystems where the flow rate will not vary by more than 10% of the average flow.

Solution 1

Solution 2

100 mts

50 mts

50 mts

20 mtsReduction Ration 2 : 1 Reduction Ration 2.5 : 1

100 mts

50 mts

50 mts

20 mtsReduction Ration 2.5 : 1Reduction Ration 2 : 1

Orifice Plate

30 mts

25 mtsHead loss over valve = 5mts

25 mtsReservoir

2 mts

Float Pilot Valve

Orifice PlateHead loss overorifice plate = 23mts

Open Discharge Systems.

When a valve is situated very near the end of a pipeline and the pipeline discharges into atmosphere, cavitation can occur.

This is typical in installations involving level control valves and relief valves.

By installing an orifice plate directly after the valve, potential cavitation and damage can be prevented from occurring.

This is not applicable when the valve discharges directly into atmosphere.



OPEN - CLOSE valves are required.

Low pressure differential is required.

The controlled media is a very dirty or abrasive liquid.

The control media is different from the controlled media (within the pipeline) e.g. Pneumatic control of water network.


Extreme fluctuations in network operating conditions areanticipated.

No Flow (shut off) situations are expected.


The Closed Valve

1 Selector Valve

The Open Valve

2 Selector Valve


3 Selector Valve


The Closed Valve

1 “a” “b”

The Open Valve

2 “a” “b”


3 “a” “b”

The two way system.


Sensitive regulation at low pressure is required.

A pressure differential is required at all operating conditions.

Little pressure reduction is required.

Simplicity of control and setting of the valve and systemare essential.

NO flow (shut off) regulation is required.


When full opening of the control valve is required for absoluteminimum pressure loss under certain operating conditions.

When the control media is not the same as the controlledmedia in the pipeline.

When the controlled media is very dirty or abrasive.

Pilot Valves.Valve accessories -

Questions relating to hydraulic relays.

Understanding electric solenoid valves.

Other devices and fittings.

A few commonly used valve examples - Open / Close Valves.

Pressure Regulating Valves.

Brass Pilot Valve Range

3WUI

Universal

3 Way

Pressure Reducing & Sustaining

16 Bar

1 to 12 Bar

1/4"

Fem. BSP or NPT

40 to 200 mm

2WPR

Universal

2 Way

Pressure Reducing

16 Bar

1 to 12 Bar

1/4"

Fem. BSP or NPT

40 to 200 mm

68-500

Relief

2 Way

Quick Relief with Built in Needle Valve

16 Bar

1 to 12 Bar

1/4"

Fem. BSP or NPT

40 to 200 mm

Model

Pilot Type

Control System Type

Function

Maximum Pressure Rating

Pressure Setting Parameters

Port Connection Sizes

Port Threads

Suitable for Valve Sizes

Plastic Pilot Valve Range

Model

Pilot Type

Control System Type

Function

Maximum Pressure Rating

Pressure Setting Parameters

Port Connection Sizes

Port Threads

Suitable for Valve Sizes

XR 100

Pressure Reducing

3 Way

Pressure Reducing with Built in Manual Override

10 Bar

1 to 6.5 Bar

1/8“

Fem. BSP

40 to 200 mm

Pressure Reducing, Sustaining & Relief

XR 101

Universal

3 Way

10 Bar

1 to 6.5 Bar

1/8“

Fem. BSP

40 to 200 mm

Pressure Reducing with Built in Manual Override

SG 2000

Pressure Reducing

2 Way

10 Bar

1 to 7 Bar

1/8“

Fem. BSP

40 to 200 mm

What is a hydraulic relay ?

Provide a few examples of hydraulic relays commonly used in the irrigationindustry ?

How does a hydraulic relay work ?

Provide a few examples of where a relay would be used ?

A hydraulic relay is a hydraulic device which actuates change within a hydraulic network on receipt of

an hydraulic signal.

What is a hydraulic relay ?

The Shastomit - A 3 way normally open relay manufactured by Arad Dalia of Israel

The Shastomon - A 3 way normally closed relay also manufactured by Arad Dalia of Israel.

The Matmar - A 3 way universal relay manufactured by Bermad of Israel.

A few examples of hydraulic relays commonly used in the irrigation industry ?

The G2000 - A 3 way universal relay manufactured by Mad Takin of Israel.

How does a hydraulic relay work ?

The deactivated mode The activated mode

Remote Operation

42

3

1

4

OpenClosed

Auto

OpenClosed

Auto

Remote Operation

OpenClosed

Auto

Auto

OpenClosed

42

3

1

4


• Example 1 - Controlling a valve remotely using the local pressure at the valve.


• Example 1 - Controlling a valve using the local pressure at the valve.

Description - The control panel is often distant from the valves which are controlled using hydraulic tube as the interfacebetween the control panel and the valve.

Problems experienced - Generally slower and sluggish reaction time when opening and closing the valve.

6 0

GULF

0 06

Hydraulic command tube to valve laid over distances of 50 meters or more

Irrigation control valve

Location of irrigation

control panel and solenoids.

WITHOUT A RELAY


• Example 1 - Controlling a valve using the local pressure at the valve.

Description - The control panel is often distant from the valves which are controlled using hydraulic tube as the interfacebetween the control panel and the valve.

Benefits - Quicker valve reaction time when opening and closing the valve.

6 0

GULF

0 06



Hydraulic command tube to valve laid over distances of 50 meters or more


V.

P. C.

Com.

Hydraulic Relay

WITH A RELAY


• Example 2 - Overcoming elevation problems within a hydraulic control system.



• Example 2 - Overcoming elevation problems with in a hydraulic control system.

Description - The control panel is often positioned higher than the valves which are controlled using hydraulic tube asthe interface between the control panel and the valve.

Problems experienced - It is unlikely that the valve will open or if the valve does open, it will not open fully.

6 0

GULF

0 06


Elevation difference between the control solenoid (valve vent) position and the valve exceeds 1 meter



WITHOUT A RELAY


• Example 2 - Overcoming elevation problems with in a hydraulic control system.

Description - The control panel is often positioned higher than the valves which are controlled using hydraulic tube asthe interface between the control panel and the valve.

6 0

GULF

0 06




Elevation difference between the control solenoid (valve vent) position and the valve exceeds 1 meter

V.

P. C.

Com.

Benefits - Positive and quick valve opening and closing.

Note !!! A suitable spring should be selected for each relay, to accommodate the elevation difference between each valve and the control panel.

WITH A RELAY


• Example 2 - Overcoming elevation problems within a hydraulic control system.

• Example 3 - Inverting a back flush valves operation.




Description - Most irrigation filters are fitted with automatic back flush valves. If two separate valves are used for to achieve the back flush operation a relay is required to swap the action of the two valves simultaneously.

Back flush valve during normal operation

Normally Open Valve(main valve)

Normally Closed Valve(flush valve)

Hydraulic Relay

During normal operationthis valve vents to open

During normal operationthis valve is closed



Description - Most irrigation filters are fitted with automatic back flush valves. If two separate valves are used for to achieve the back flush operation a relay is required to swap the action of the two valves simultaneously.

Back flush valve during flush mode

Normally Open Valve(main valve)

Normally Closed Valve(flush valve)

Hydraulic Relay

During flush modethis valve closes.

During flush mode thisvalve vents to open.

What is a solenoid valve ?

How a solenoid valve works.

The different modes of powering solenoid valves.

The difference between a 2 way a 3 way solenoid valve.

The difference between normally open and normally closed solenoid valves.

What is a solenoid valve ?

It can therefore be said that a Solenoid Valve is thus an electrically operated device for controlling the passage of liquid or gas or the likes through pipe.

A Valve can be defined as an automatic or other device for controlling the passage of liquid or gas or the like through pipe, etc.

A Solenoid can be defined as a cylindrical coil of wire which when an electric current is passed through, it behaves as a bar magnet.


To better understand the operation of a solenoid valve, it would be beneficial to acquaint yourself with the components withinthe solenoid operator.

The solenoid bobbin is wound withcopper wire to create the solenoid

coil.

The solenoid housing is equippedwith the solenoid coil.

The plunger housing is equippedwith the plunger.

The plungershaft.

The plunger is fitted with the plunger seal.

The plungerseal.

The solenoid housing is equippedwith the plunger housing and

filled with potting resin.

The complete solenoid operator

The Operators Components


How the solenoid operator functions.

The Operator Coil The Operator Coil

The Plunger The Plunger

De - Energized mode Energized mode

In the de-energized mode, theplunger moves freely in the hollow

core of the solenoid operator.

Generally, the plunger is fitted with aspring in order to force the plunger

in a downward motion.

In the energized mode, the operator coil creates a magnetic field, which draws the plunger into the hollow

core of the solenoid operator.

The plunger is held in this position,either by a continual electrical supply

to the solenoid operator coil(in the case of most standard ac or dc solenoids) or by means of a

magnet (as used in a dc latchsolenoid).


The solenoid valves components.

The solenoid operator

The solenoid base

Example of a typical 3 way solenoid valve and base.

A complete solenoid valve includingoperator and base.

It should be noted that not all solenoidvalves are fitted with bases, as in thiscase. Many plastic injection mouldedelectrical irrigation valves use 2 way solenoid operators mounted directlyonto the valves lid.


Cross section of a 3 way solenoid valve.

Port 1.Port 2.

Port 3.

The solenoid operator is fitted to a valve base which is equippedwith ports. The plunger within the solenoid body is fitted with rubber

seals on either end.

De-activated

Port 2. Port 1.

Port 3.

When the solenoid is de-activated, the plungeris forced down by the presence of a spring.In so doing, port 1 is sealed and ports 2 and 3are connected.

Port 2. Port 1.

Port 3.

Activated

When the solenoid is activated, the plunger islifted by the magnetic force into the coil and

port 3 is sealed and ports 1 and 2 areconnected together.

The different modes of powering a solenoid valve.Standard AC (alternating current) solenoids are built to operate using a cyclic sine wave power input such as thatdetailed below.

AC Cyclic Sine Wave

All DC (Direct Current) solenoids operate using a smooth power such as the wave form below. DC power is polarized while AC power is not.

DC Smoothed Wave

Some AC solenoids are in fact DC solenoids which use AC power which is converted within the solenoid to DC by wave rectification using diodes.

AC Cyclic Sine Wave DC Smoothed Wave

converted to

There are two types of AC solenoid valves used in the irrigation industry.

1. The standard AC solenoid valve.

2. The DC solenoid valve which uses AC power that is converted through rectification to DC

Both of the above solenoids require power continuously, during operation.

The different modes of powering a solenoid valve.

There are also two types of DC solenoids is use.

1. The standard DC solenoid (seldomly used in irrigation applications.)

2. The magnetic latch DC solenoid.

The standard DC solenoid requires power all the time duringoperation. The magnetic latch solenoid switches from one positionto the other by receiving an electrical pulsed signal. The plungeris held in position by the magnet. It is possible to have either2 wire

AC Solenoid Valves

DC Solenoid Valves

Standard 24 volt AC solenoid coil

3 wire DC magneticlatch solenoid coil

2 wire DC magneticlatch solenoid coil

Magnet

or 3 wire DC magnetic latch solenoid operators.

The different modes of powering a solenoid valve.

Some important differences between AC and DC powered solenoids.

DC power cannot be conveyed effectively over long distances and therefore AC power is the preferred source in largersystems.

As DC power is polarized, it has a tendency to cause electrolysis at poor joins underground which results in corrosionand joint breakdown. This problem is not as apparent in AC systems.

AC power is not as effective as DC in the operation of the solenoid. The cyclic power supply is the main cause of this.Many companies have thus a preference to using DC coils.

DC solenoids have no inrush current. This includes solenoids that use AC power which is converted to DC within thesolenoid itself.When calculating the wire sizes for standard AC solenoids, it is important to take the extra inrush loadrequired during initial activation into consideration. This is not required in DC solenoids.

DC magnetic latch solenoids require a minimum amount of power and are therefore very effective forbattery and solar operated systems.

Voltages/Frequency Current Control System TypeFlow Pattern

Wattage Materials

6 Direct 2 & 3 Way NO or NC Various Brass Base and Plastic Coil Housing

9/12 Direct 2 & 3 Way NO or NC 2 Wire Latch Type Plastic Base and Plastic Coil Housing


18 Direct 2 & 3 Way Universal 2 or 3 Wire Latch Type Plastic or Brass Base and Plastic Coil Housing






12 @ 50 or 60 Hz Alternating 2 & 3 Way NO or NC Various Brass Base and Plastic Coil Housing

24 @ 50 or 60 Hz Alternating 2 & 3 Way NO or NC 2.5, 3 , 5.5 & 8 Plastic or Brass Base and Plastic Coil Housing





240 @ 50 Hz Alternating 2 & 3 Way NO or NC Various Brass Base and Plastic Coil Housing



Commonly used solenoid valves.

A few examples of commonly used solenoids in the irrigation trade.

24 Volt AC 3 Waysolenoid and Base

9/12 Volt DC Latch 3 Waysolenoid and Base

Heavy Duty 24 Volt AC3 Way solenoid and Base

The difference between a 2 way and a 3 way solenoid.

2 way solenoids.

2 Way solenoids are used on internally ported single chamber hydraulic control valves,mainly on plastic moulded valves.

2 Way solenoids are not complete valves as they do not allow for the flow of water throughthe solenoid.

2 Way solenoids are only available in normally closed configuration.

3 Way solenoids are used on externally plumbed hydraulic control valves.

3 Way solenoids once fitted with a valve base become 3 way solenoid valves.

3 Way solenoid valves are available in Normally Open and Normally Closed configuration.

3 way solenoids.

A typical 2 waysolenoid operator.

A typical 3 waysolenoid operator.


Normally Open Solenoid Valves.

Port 3. Port 3.

De-activated Activated

Port 1. Port 1.Port 2. Port 2.

A normally open solenoid valve will open the valve controlled by the solenoid, when the solenoid is energized.

The relationship between the size of the hole marked "A" in port 3, the water pressure at this hole and the pulling force ofthe solenoid on the plunger when activated, determines the solenoids maximum operating pressure.

The higher the force the plungers seal exerts on the hole, the higher the pressure at port 3, can be.

“A”

“B”

Port 1 - Vent / Exhaust

Port 2 - Common

Port 3 - Pressure

To assist this action, the spring at "B" needs to be relatively soft.

The larger the hole at "A" the lower the shutoff pressure can be in port 3. Most solenoids used in the irrigation industry arerated to operate at 10 Bar.

The normally open solenoid valve is the most popular in the irrigation industry.


Normally Closed Solenoid Valves.

Port 3. Port 3.

De-activated Activated

Port 1. Port 1.Port 2. Port 2.

A normally closed solenoid valve will close the valve controlled by the solenoid, when the solenoid is energized.

“A”

“B”

Port 1 - Pressure

Port 2 - Common

Port 3 - Vent / Exhaust

The relationship between the size of the hole marked "A" in port 1, the water pressure at this port and the pushing force of thesolenoids plunger when de-activated, determines the maximum operating pressure of the solenoid valve

The higher the force the plungers seal exerts on the hole, the higher the pressure at port 1 can be.

To assist this action, the spring at "B" needs to be relatively strong.

The larger the hole at "A" the lower the shutoff pressure can be in port 1. Most solenoids used in the irrigation industry are rated tooperate at 10 Bar.

The normally closed solenoid valve is not commonly used in the irrigation industry.

3 Way Ball Valve

Com.

Pressure Selector Tee

The three way ball valve used in three way systems. One common port is connected to one of the other three ports as selected by the operator.

The inline two way ball valve is used for two way systems. This valve is a simple Open or Closed, 90 degree turn ball valve.

Needle valves are used for pinching the control passage within

the control network. The selector tee is generally used in three way systems and will only allow water to flow from one of the ports through the common port at any given time depending on which port has the higher pressure..

Inline spring loaded non return valves are used in two and three way system. Often used to convert the control valve into a check valve.

Hydraulic Fittings

Finger FiltersControl network filters

Finger filters - Available in brass and plastic in sizes 1/4m x 1/4f or 1/4m x 1/8f. Both long and short versions are available in brass. Long finger filters are used for 150mm valves and upwards.

Inline Filters - Available in brass or plastic in 1/2" and 3/4" sizes. Used mainly on two way systems.

Fittings

Plastic Fittings - A full range of fittings including, elbows, connectors, adapters, tees and nipples. Available in 8mm, 6mm, 1/4" or 1/8" connections.

Brass Fittings - A full range of fittings including, elbows, connectors, adapters, tees, nipples, sockets, etc. Available in 1/4" or 1/8"

Manual Open/Close Valve (3 Way Operation)

C

A

O C

A

O C

A

O

Overview

The valve is controlled manually by a three port selector valve which allows the user to select the "Closed" position,"Open" position or the "Auto" position for remote control operation. The control of the valve is effected effortlessly andquickly, even under high operating pressures.

Applications.

Activation of valves located in inaccessible places.Activation of valves remote from the control.Effortless activation of large valves.

Design Considerations.

Size the valve to suite:The maximum flow rateThe maximum allowable head lossThe maximum allowable velocity

C = Closed O = Open A = Automatic

Closed Open Remote

Electric Open/Close Valve with Manual Override (3 Way Operation)

Applications.

Electrically activated remote control valve.


Electric valves can be Normally open or Normally closed.This term refers to the valve and not the solenoid.

Valves operating at high pressures require non standardsolenoids.

If water is abrasive or dirty use a hydraulic relayor consider improving control network water filtration.

1

2

1

2

1

2

1

2

A. B. C. D.

Overview

The valve is controlled by an electrical solenoid valve which converts an electrical command signal into a hydraulic orpneumatic command.

Operating Position.

A - Solenoid is inactive, valve is closedB - Solenoid is active, valve is openC - 3 Way selector valve is set to manual close, valve is closed.D - 3 Way selector valve is set to manual open, valve is open. 1 is a normally open 3 way solenoid valve

2 is a 3 way selector valve

Hydraulic Remote Controlled Open/Close Valve (3 Way Operation)Remote CommandNo Remote Command

1 1“1” is a 3 wayhydraulic relay

Closed Open

Applications.

Control of remotely located valves form a common pointwhen electricity is not available or is problematic.


Relays are generally recommended when the distancebetween the valve and the control position exceeds 100m.

Smaller remote control tubes are advised to hasten theactivation of the relay.

The remote source must be equal or higher than thepressure at the valve.

Overview

The valve is fitted with a hydraulic relay which converts a remote pressure signal to a local hydraulic command, thusaccelerating the valves response. Relays are often also used to overcome elevation problems when the remote sourceis higher than the valve location. The relay needs to be equipped with the correct spring for this function.

Operating Position.

Closed - No remote signal is provided so the valve uses local pressure to close.Open - A remote signal is applied and the valve vents locally to open.

Non Slam Check Valve

Overview

The valves upper chamber is connected hydraulically into the downstream. When the upstream pressure falls below that ofthe downstream, the valve closes immediately preventing the reverse flow in the network. The flexible diaphragm ensuressoft closure, protecting the network from the damaging effects of water hammer. The closing speed of the valve is adjustable by setting the needle valve.

Applications.

Preventing drainage of uphill pump networks.


This type of valve closes slower than a conventional checkvalve and therefore some form of reverse flow can beexpected before the valve is fully closed.

This type of check valve has considerable head loss andtherefore it should be used mostly on two way operating valves.

If head loss of 10 Mts. is unacceptable, another solution should be sought.

“1” is a Needle Valve

1. 1.

Closed Open

Pressure Reducing Valve (2 Way Operation)

A. B.

Applications.

Control of network pressure in industrial, water supply,high rise buildings and agricultural systems.


Valves fitted with two way operating systems createpressure loss regardless of flow. Two way operationshould only be utilized when the required loss is greaterthan 10 Mts. under all operating conditions.

When the required reduction over the valve is high and theflow rate is low, it is advisable to install a smaller bypassvalve in parallel with the larger valve.

Beware of cavitation and reduction ratios.

Overview

The valve reduces high upstream pressure to create a lower, stabilized downstream pressure. The pressure reducing valvewill accurately control downstream pressure regardless of upstream pressure or flow rate fluctuation. This valve will alsoprovide pressure control under no flow conditions

Operating Position.

A - The valve will close when the downstream pressure exceeds the pre-set limit on the pilot. Complete closure will occur under shutoff conditionsB - The valve will open until the sensed downstream pressure is equal to or greater then the pilots set pressure.C - Under normal operation, the valve is in the regulation mode.

C.

1. 2. 1. 2. 1. 2.

“1” is a needle valve “2” is a two way pilot valve

Pressure Reducing Valve (3 Way Operation)

A. B.

Applications.

Pressure control mainly used in agriculture low pressure networks.Pressure control in low pressure pumping systems with fluctuating flows.


The three way system should be selected in systemswhere minimal or zero pressure differential is requiredunder certain operating conditions.

The response time of a valve fitted with 3 way control canbe delayed and it is advisable to consider the installationof a quick relief valve, downstream of the PRV, to protect the system.

Do not use the three way control system when no flowconditions are envisaged. Beware of cavitation.

Overview.

The valve reduces high upstream pressure to create a lower, stabilized downstream pressure. When upstream pressuredecreases to the required downstream pressure, the valve opens fully. Minimal friction loss is created.

Operating Position.

A - The downstream pressure exceeds the pilots setting,causing the valve to partially close to reduce the downstream pressure.B - The downstream pressure is lower than the set level causingwater to be vented form the control chamber, opening the valve.C - The upstream pressure is lower than the pilots setting causingthe valve to open fully.D - The downstream is balance with the set pressure causing thepilot to close. The valve will remain in this position.

C. D.

1. 1. 1. 1.

“1” is a 3 Way Pressure Reducing Pilot Valve.

Pressure Sustaining Valve (3 Way Operation)

Applications.

Limiting the flow in downhill networks.Downstream of high elevation areas to ensure sufficient pressure isavailable to these areas.As a relief valve to relieve excess pressure out of the system.


Sustaining valves are fitted into the pipeline where relief valvesare fitted on a tee junction to relieve water from the system.

The response time of a valve fitted with 3 way control can bedelayed when changing from the fully open position. Asustaining/ relief valve is not suitable to protect the systemagainst shutoff conditions. Use a quick relief valve for systemprotection

Beware of cavitation.

Overview

The valve remains closed while upstream pressure is below the pre-set pressure on the pilot. When the upstream pressureincreases the pilot limits the valve opens to a position keeping the required set upstream pressure. The pilot allows the valveto open fully when upstream pressure exceeds the pilots setting.

Operating Position.

A - The upstream pressure is lower than the pre-set level of the pilot causing the valve to close.B - The upstream pressure increases to the pre-set level of the pilot allowing the valve to open partially.C - The upstream pressure is equal to that of the pilots setting causing the pilot to close and locking the valve in this position.D - The network pressure is higher than the pilot pre-set pressure causing the valve to open fully. “1” is a 3 Way Universal Pilot Valve.

A. B. C. D.

1. 1. 1. 1.

Quick Pressure Relief Valve (2 Way Operation)

Applications.

Preventing pressure surges in the system.


Relief valves are not modulating valves and must not be usedfor this purpose.

A quick acting pressure relief valve should be selected todischarge between 50 - 80% of the systems nominal flow.

The following valve selection is recommended for short periodsof flow.

50mm valve up to 100 m³/hr 65mm valve up to 160 m³/hr80mm valve up to 250 m³/hr 100mm valve up to 400 m³/hr150mm valve up to 850 m3/hr

Overview

The valve is mounted on a tee junction in the network and adjusted to open instantly whenever the network pressure exceeds the pre-set pressure of the pilot. This valve therefore protects the network from dangerous pressure surges. The needle valve allows for adjustingthe closing speed of the valve.

Operating Position.

A - The pressure in the network is below the pilots setting. The valve remains closed.B - The network pressure exceeds the pilots setting causing the valve to open instantly. Full opening is achieved.C - The network pressure falls below the pre-set level of the pilot and the valve begins to close. Speed of closure is dependent on the needle valve setting.

“1” is a Needle Valve “2” is a Quick Relief Pilot Valve.

A. B. C.

1. 2. 1. 2. 1. 2.

Needle valve to adjust the

valves closing speed.

68-500 Brass Pilot Valve

BACK

Basic Valve with Quick Acting Brass Pressure Relief Pilot – 2 Way

INOUT

CLOSE

68-500 Brass Pilot Valve

BACK

Basic Valve with Quick Acting Brass Pressure Relief Pilot – 2 Way

INOUT

OPEN


valves closing and opening

speed.

2WPR Brass Pilot Valve

BACK

OPEN

Basic Valve with Brass Pressure Reducing Pilot Valve – 2 Way

INO

UT


valves closing and opening

speed.


BACK

CLOSE


INO

UT


BACK

REGULATE


INO

UT

Com.

Closed

Auto

OpenInOut

Sense

Basic Valve with Manual Override, Universal Pilot fitted for reducing operation, 3 way

Universal Pilot

3WUI Brass Pilot Valve

If the downstream pressure is LOWER than the spring tension, the valve will OPEN.

BACK

Com.

Closed

Auto

OpenInOut

Sense

Basic Valve with Manual Override, Universal Pilot fitted for reducing operation, 3 way

Universal Pilot


If the downstream pressure is HIGHER than the spring tension, the valve will CLOSE.

BACK

Com.

Closed

Auto

OpenInOut

Sense

Basic Valve with Manual Override, Universal Pilots fitted for reducing operation, 3 way


If the downstream pressure is EQUAL to that of the spring tension, the valve will be in the REGULATED position.

Fluid locked in upper

chamber in regulated

mode.

REGULATION

BACK

XR 100 - Plastic Pilot Valve

Basic Valve with Pressure Reducing Pilot Valve (Built in Manual Override) – 3 Way.

2

3

4

1

5

Open Closed

Auto

MANUALLY CLOSED

BACK



2

3

4

1

5

Open Closed

Auto

MANUALLY OPEN

BACK



2

3

4

1

5

Remote signal from solenoid valve at RX unit, etc.

AUTO CLOSED

Open Closed

Auto

BACK

If the remote signal is weak, use the RCU (Remote

Command Unit) (below 3 Bar)



2

3

4

1

5

AUTO OPEN

Open Closed

Auto


BACK



2

3

4

1

5

REGULATION IN AUTO OPEN OR MANUAL OPEN POSITIONS


If the downstream pressure is LOWER than the spring tension, the valve will OPEN.

BACK



2

3

4

1

5



If the downstream pressure is HIGHER than the spring tension, the valve will CLOSE.

BACK



2

3

4

1

5



If the downstream pressure is EQUAL to that of the spring tension, the valve will be in the REGULATED position.

BACK

Fluid locked in upper

chamber in regulated

mode.

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