regulators and flowmeters ret 2274 respiratory care theory 1 module 3.0
TRANSCRIPT
Regulators and Flowmeters
RET 2274
Respiratory Care Theory 1
Module 3.0
Regulators and Flowmeters
Regulating Gas Pressure and Flow Cylinder gases exert too high of a pressure
for use with respiratory equipment, and must be reduced to a working pressure of 50 psig (pounds per square inch gauge)
This standard pressure can be applied to power devices such as IPPB, pneumatic precursors, ventilators, etc.
Reducing valves are used to reduce high pressure to a working pressure
Regulators and Flowmeters
High-Pressure Reducing Valves Two types
Single Stage Multiple Stage
Available as preset or adjustable
Regulators and Flowmeters
High-Pressure Reducing Valves Preset Reducing Valve
Automatic adjustment of the diaphragm-spring combination keeps the pressure in the high-pressure chamber at a near-constant 50 psig; thus the name preset
Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description
Regulators and Flowmeters
High-Pressure Reducing Valves Preset Reducing Valve
(H) High-Pressure gas inlet
(G) Valve stem
(B) Pressure gauge
(E) Flexible diaphragm
(D) Ambient-pressure chamber(F) Spring
(C) High-pressure chamber
(A) High-pressure inlet
(I) Gas outlet
Regulators and Flowmeters
High-Pressure Reducing Valves Adjustable Reducing Valve
Some devices need variable pressures
The adjustable reducing valve allows a change in outlet pressure via a threaded hand control attached to the diaphragm
Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description
Regulators and Flowmeters
High-Pressure Reducing Valves Multiple-Stage Reducing Valve
Can be preset or adjustable Reduces pressure in two or more steps
First stage – pressure is lowered to an intermediate level (200 – 700 psig)
Second stage – pressure is decreased to working level (50 psig)
Provide more precise and smooth flow control
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Flowmeters are needed to set and
control the rate of gas flow to a patient, either from a station outlet or a high-pressure cylinder
When using a a high-pressure cylinder as the gas source, a regulator (reducing valve plus flowmeter) is required
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Three categories of flowmeters
Flow restrictor
Bourdon gage
Thorpe tube
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Flow restrictor
Consists of a fixed orifice calibrated to deliver a specific flow at a constant pressure (50 psig)
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Fixed Orifice Flowmeter
Provide specific flow rate settings by selecting or adjusting an outlet orifice size
This unit incorporates a reducing valve and fixed orifice flowmeter
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Bourdon Gage
A flow-metering device that is always used in conjunction with an adjustable pressure reducing valve
It is a fixed orifice, variable-pressure, flow metering device
Regulators and Flowmeters
Bourdon Gage Hollow tube
straightens as gas pressure increases – increasing flow through the fixed orifice
Will work in any position – ideal for transport
Regulators and Flowmeters
Bourdon Gage Not back-pressure
compensated
As resistance to flow increases, the indicated flow reading becomes inaccurate
Regulators and Flowmeters
Low-Pressure Gas Flowmeters Thorpe Tube
Always attached to a 50 psig gas source – either a station outlet or a pressure reducing valve
It is a variable orifice, constant-pressure flow-metering device
Measures true flow
Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description
Regulators and Flowmeters
Thorpe Tube Two types
Pressure uncompensated vs. Pressure compensated
Regulators and Flowmeters
Thorpe Tube Pressure uncompensated
Uncompensated for backpressure Needle valve is proximal to the
Thorpe tube If pressure is applied distally to the
tube, e.g., kinked tubing, flow indication may be lower than delivered flow
Regulators and Flowmeters
Thorpe Tube Pressure compensated
Compensated for backpressure Needle valve is distal to the Thorpe
tube If pressure is applied distally to the
tube, e.g., flow-restricted equipment or kinked tubing, it will have NO effect on the flowmeter’s performance. The float will be an actual reading of flow delivered
Regulators and Flowmeters
Ranges of Flowmeters High-range
0 – 75 L/min (5-L/min intervals) CPAP and high-flow
oxygen delivery devices
Regulators and Flowmeters
Ranges of Flowmeters Low-range
0 – 3 L/min (1/4-L/min intervals) Pediatric and COPD
patients
Regulators and Flowmeters
Ranges of Flowmeters Standard
0 – 15 L/min (1-L/min interval) Most oxygen delivery
devices
Regulators and Flowmeters
Correctly Reading a Flowmeter Ball-float flowmeter
Read from the middle of the ball
6 L/min
2 L/min
Regulators and Flowmeters
Correctly Reading a Flowmeter Bobbin flowmeter
Read from the top of the bobbin
2 L/min
Because the RT has to transport a patient using oxygen, they should select an E cylinder with an adjustable regulator that includes a Bourdon gauge (unaffected by gravity)
Regulators and Flowmeters
Mini Clinic – Select the Proper Device
Problem:
An RT has an order to transport a patient to radiology with oxygen. What equipment should the therapist select?
Solution:
Because pneumatically powered ventilators require 50 psig and no central oxygen outlets are available, the RT needs a preset reducing valve and a large H cylinder of oxygen.
Regulators and Flowmeters
Mini Clinic – Select the Proper Device
Problem:
An RT has to set up a pneumatically powered ventilator with oxygen in the ambulatory clinic, where there are not oxygen outlets. What equipment should the therapist select?
Solution:
Because moderns ICUs have central wall outlets for oxygen, The RT needs only select a flowmeter. A compensated Thorpe tube is required for metering flow through high-resistance equipment such as jet nebulizers
Regulators and Flowmeters
Mini Clinic – Select the Proper Device
Problem:
An RT has to set up oxygen therapy with a jet nebulizer for a patient in the ICU. What equipment should the RT select?
Solution:
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder1. Select the proper gas cylinder
Ensure content of cylinder by checking the label
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder2. Remove protective covering from cylinder
outlet
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder3. “Crack” the cylinder to remove dust, debris
and moisture
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder4. Select the appropriate gas regulator
Ensure that a plastic washer is in place
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder5. Attach the gas regulator to the cylinder valve
It should fit into place easily - DO NOT FORCE IT!!!
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder6. Tighten the fittings in place
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder7. Open the cylinder valve SLOWLY and
pressurize the regulator, note the amount of gas pressure in tank – listen for leaks
Cylinder Wrenches
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder8. Set the flowmeter to the prescribed flow rate
and attach the oxygen delivery device
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder9. Place the oxygen delivery device on the
patient and monitor vital signs
Regulators and Flowmeters
Attaching a Regulator to a Gas Cylinder9. Place the oxygen delivery device on the
patient and monitor vital signs