document sample no. 2

Doc. ID / Version: XXXXXX / A

Doc. Owner: YYYYY

DOC. TYPE: Standard Operating Procedure

Program:

Miscellaneous

Project:

Equipment Maintenance

Coolant Centrifuges: Cleaning Procedure

DOCUMENT CHANGE & HISTORY RECORD

NameLast

UpdateStatus Version Comment

Paul F. Geer 8-Jul-08 Draft A Initial release.

Applicable Documents

Ref. Title Doc. Id[1.1]

[1.2]

Tooling Required

Description Part Number

1 CROWBAR

1 ALLEN WRENCH OR DRIVE RATCHET

For change control: Reviewers: Approved by: For info:Paul F. Geer

Author: Paul F. GeersalklPages Incl. cover : 10

© LOGOS 2008. All rights reserved.Reproduction in whole or in part is prohibited without the prior written consent of LOGOS.

Standard Operating Procedure Doc ID / Version: XXXXXX / A

TABLE OF CONTENTS

1 GENERAL..............................................................................................................................3

1.1 PURPOSE.......................................................................................................................3

1.2 SCOPE............................................................................................................................3

2 RESPONSIBILITIES...............................................................................................................4

2.1 TECHNICIAN...................................................................................................................4

2.2 MANAGEMENT...............................................................................................................4

3 PROCESS DEFINITION.........................................................................................................5

3.1 OVERVIEW......................................................................................................................5

3.2 COMPONENTS REFERENCED.....................................................................................5

4 required steps.........................................................................................................................7

LIST OF FIGURESFigure 3.1 View of Centrifugal Filtration System.....................................................................................5Figure 3.2 The Centrifuge Rotor.............................................................................................................6Figure 4.1 Control Panel: Location of Centrifuge-Off Button...................................................................7Figure 4.2 Isolating the Centrifuge from Coolant Flow............................................................................7Figure 4.3 Opening the Rotor Housing...................................................................................................8Figure 4.4 Cover Safety Hook................................................................................................................. 8Figure 4.5 Bolt Locations on the Rotor Cover.........................................................................................9Figure 4.6 Removing the Rotor Cover from the Centrifuge Housing.......................................................9Figure 4.7 Control Panel: Location of Centrifuge-On Button.................................................................10

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1 GENERAL

1.1 PURPOSE

1.1.1 The document outlines the procedure for cleaning centrifuge purification systems of the type shown in Figure 3.1.

1.1.2 The control of coolant purity is an essential part of glass processing. Through typical operations associated with fabricating elements, particulates resulting from glass abrasion contaminate the coolant used in cutting and grinding equipment. Such contamination can have a significantly negative impact on workpiece quality, such as increased levels of surface scratching or roughness. These problems can lead to production delays due to time spent on reworks, or locating replacements.

1.1.3 To minimize waste, maintain workpiece quality, and keep on schedule, a purification system must be used to continuously process the coolant during production. Optical Generating employs a centrifuge system whose operation consistently meets workpiece requirements. However, the system’s success comes only when regular maintenance is performed to sustain its efficiency; if not regularly cleaned, the centrifuge loses its ability to remove particulates due to the build-up of sludge. Thus, maintenance has an important role in achieving the workpiece quality desired.

1.2 SCOPE

1.2.1 Although this document’s focus is on the equipment shown in Figure 3.1, the cleaning procedure it outlines can be applied to any centrifuge with a removable basket liner (see call out in Figure 3.2).

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2 RESPONSIBILITIES

2.1 TECHNICIAN

2.1.1 The cleaning of the centrifuge is tracked according to the time it was performed, and the person who performed it. For this reason, the technician is required to record his or her signature, and date, on a log sheet maintained for the equipment.

2.1.2 The hinged cover on the centrifuge housing must be in a secure position, before the technician can perform any cleaning steps. A safety hook must be used as a precaution against injury to arms or hands. The technician is not permitted to use any means other than the safety hook for keeping the housing open.

2.2 MANAGEMENT

2.2.1 The management has the responsibility of ensuring personnel observe the above-mentioned requirements, and that they follow all procedures as stated in this document. If necessary, the manager or supervisor in Optical Generating should mandate training for newly hired personnel.

2.2.2 The management must ensure that equipment has the tools required for carrying out maintenance safely. Wherever there is a risk of injury, the supervisor or manager must not permit maintenance until the necessary tools are in place for eliminating the risk.

2.2.3 It is management’s responsibility to monitor the frequency of this procedure’s application. The log sheets must be reviewed to ensure the cleaning procedure is carried out 2 times a week, as instructed in this document.

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3 PROCESS DEFINITION

3.1 OVERVIEW

3.1.1 In general, milling machines require coolant for temperature control, and for washing away particles from workpieces being ground or cut. After being cycled through the machines, the coolant runs off the equipment work areas and then into a chiller. From the chiller, it then flows into the collection tank for processing through the centrifuge system. The centrifuge’s high-speed rotation separates the particulates from the pure coolant liquid. Finally, the purified coolant is then recycled back to the machines.

3.1.2 In the centrifuge’s operation, a basket liner inside a rotor traps the glass particulates suspended in the coolant. Over time, the particulates collected eventually form a layer of sludge on the basket liner, which can affect the centrifuge’s efficiency. Therefore, a regular cleaning of the basket liner is required to preserve the centrifuge’s normal functioning. Without this regular cleaning, the sludge layer will continue to thicken on the liner, causing increased levels of contamination in the recycled coolant.

3.1.3 The Optical Generating Department requires the centrifuge be cleaned twice a week, as a precaution against contaminants affecting element fabrication.

3.2 COMPONENTS REFERENCED

3.2.1 Figure 3.1 shows the centrifuge system as arranged on the Generating Department’s shop floor. The coolant chiller is also shown.

Figure 3.1 View of Centrifugal Filtration System

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3.2.2 Figure 3.2 provides a close-up view of the centrifuge rotor. The rotor housing is open to show the location of the sludge basket liner, which is the component handled in the cleaning operation discussed in this procedure. The figure also calls out the safety hook, which securely holds open the hinged cover for maintenance operations.

Figure 3.2 The Centrifuge Rotor

3.2.3 To prevent injury, technicians must remember to use the safety hook for keeping the hinged cover in an upright position, as shown above.

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4 REQUIRED STEPS4.1 Power to the centrifuge rotor must be switched off before the housing is opened. Press

the CENTRIFUGE OFF button on the front panel, to deactivate the equipment (see Figure 4.1).

Figure 4.3 Control Panel: Location of Centrifuge-Off Button

4.2 Two valves must be closed to prevent coolant leaking back into the centrifuge:

4.2.1 Close the valve indicated in Figure 4.2, by turning the red lever.

Figure 4.4 Isolating the Centrifuge from Coolant Flow

4.2.2 Close the gray “T” valve mounted on the wall adjacent the centrifuge and chiller. Although not shown directly, this valve is found in the direction called out Figure 3.1.

Note: The above mentioned valves must remain closed throughout the entire cleaning process. The valves are reopened only when the centrifuge is completely closed and ready for operation.

4.3 Unlock the hinged cover of the centrifuge. Turning a knob on the top surface, at the edge shown in Figure 4.3, unlocks the cover.

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Figure 4.5 Opening the Rotor Housing

Note: The above knob operates a screw for sealing the cover against the centrifuge opening. A gasket underneath the cover creates the seal. When the knob is turned the maximum distance outward, there will be an audible “click”, indicating that the seal is broken. The housing is ready for opening after this sound.

4.4 Lift the cover off the centrifuge opening, and latch the raised end with the safety hook, as shown in Figure 4.4. To latch, slip the loop over the thumbscrew (i.e., over the threaded part emerging through the cover) and then secure the loop with the lug nut.

Figure 4.6 Cover Safety Hook

WARNING: DO NOT CLEAN THE CENTRIFUGE WITHOUT PROPERLY SECURING THE COVER. Not using the safety hook introduces the risk of serious injury, as an unlatched cover may fall on arms or hands.

4.5 Now unlock the rotor cover, by loosening four (4) bolts threaded into the flanged top, shown in Figure 4.5. The bolts are very tightly threaded into the cover; use a suitably sized allen wrench, or drive ratchet with an appropriately sized allen head, to loosen and unthread the bolts in the CLOCKWISE direction.

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Figure 4.7 Bolt Locations on the Rotor Cover

WARNING: Splashing of coolant may occur from handling the rotor cover for removal. Place a rag over the centrifuge opening for protection against exposure.

4.6 Using a crowbar, pry the rotor cover out of its seating in the centrifuge housing. To obtain mechanical advantage, insert the crowbar’s tapered end between the centrifuge bowl and the cover’s flanged end, as shown in Figure 4.6. When the flange is sufficiently raised for handling, lift the rotor cover out of the centrifuge to expose the bowl, and the basket liner.

Figure 4.8 Removing the Rotor Cover from the Centrifuge Housing

4.7 By grabbing two handles at the top, lift the basket liner out of the centrifuge bowl, and carry it to the sludge drum designated for hazardous waste. Dispose of the sludge cake (i.e., the layer of glass particulates) collected in the basket.

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Note: The sludge drum is generally stored near a large coolant collection station in the shop. An enclosed area, accessed only through a steel door, isolates both the collection station and the drum from workshop areas.

4.8 Return the empty sludge basket to the centrifuge, inserting it back into the centrifuge bowl. Then insert the rotor cover back over the centrifuge bowl. Make sure the cover is correctly seated in the opening: gently tap on the flange surface with a rubber mallet, nudging the cover into a tight fit.

4.9 Lock the rotor cover in the centrifuge, by threading and tightening the bolts removed in Step 4.5. Use an allen wrench or drive ratchet of the correct size, as directed for removing the bolts. Place a rag over the centrifuge opening to prevent exposure to splashing coolant.

4.10 Enclose the rotor, unlatching the hinged cover and locking the centrifuge housing: remove the lug nut, seat the cover over the opening, and then turn the knob of Step 4.3 for a tight seal. When not in use, the lug nut is placed on a magnetic strip attached to the equipment framework.

This completes the procedure for cleaning the coolant purification centrifuge. Once the hinged cover is closed, the centrifuge can be restored to normal operations.

4.11 Open the valves mentioned in Step 4.2, permitting coolant to flow through the centrifuge. Then, on the control panel, press the CENTRIFUGE ON button to restore the normal operation of the system (see Figure 4.7).

Figure 4.9 Control Panel: Location of Centrifuge-On Button

4.12 Sign and date the cleaning log sheet for the centrifuge, per the requirements stated in Chapter 2.

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