2020 Tech Report May-June

TECHNICAL REPORT

THE

REFRIGERATING ENGINEERS & TECHNICIANS ASSOCIATION | MAY/JUNE 2020

FLOAT SWITCH TESTING AUTHORIZED USERS: This procedure is designed for use by Refrigeration Service Technicians to perform testing of liquid level float switches. You must consult facility policy and procedures concerning liquid level float switches. You must follow the facility procedure. This procedure is considered minimum requirements. This procedure is to be used in addition to facility procedures. OBJECTIVE: Maintenance Procedures are designed to give general guidance when performing maintenance activities. No procedure is appropriate for every situation. Refrigeration Service Technicians should not attempt any repair which is beyond their training. CONCERNS: Careful attention to operating conditions is extremely important during this procedure. The primary incident we are trying to prevent is injury to personnel. Additionally, our goal is to avoid system upsets during testing which can lead to operational issues as well as potentially leading to an ammonia release, or mechanical damage of system components. Use by others is not authorized under any circumstances.

REFERENCES: Additional information is available to personnel performing inspections. This information is not required to be reviewed. However, those technicians wishing further information may seek these sources out:

• International Institute of Ammonia Refrigeration (IIAR) Bulletin #109 • International Institute of Ammonia Refrigeration (IIAR) Bulletin #110 • Refrigerating Engineers and Technicians Association (RETA) Industrial Refrigeration Books III and IV • IIAR-5 (Start-up and Commissioning of Closed-Circuit AmmoniaMechanical Refrigerating Systems) • IIAR-6 (Maintenance and Inspection of Closed- Circuit AmmoniaMechanical Refrigerating Systems) (*When released) • Refrigerating Specialties Bulletin 61-10G, TYPE LL, LLC, LLX, LLS, LLSC, LLXS, LLA, LLAC, LLAX

• Hansen Bulletin HLL-2c

• Operation andMaintenance Manuals for facility equipment • Facility policies located in the facility’s Ammonia Refrigeration Compliance Program

RETA TECHNICAL REPORT PAGE 1

• Other PPE as outlined by the facility. This may include a wide range of possible equipment, such as confined space entry equipment, retrieval harnesses, dust masks, etc… Tools and Materials: • Radio or Cell Phone Communications • StandardMechanic’s Tools • Transfer Hose (Ammonia Rated – See Transfer Hose Diagramon Page 3) • Pipe Plugs • A Barrel of Water • Standard Operating Procedure (SOP) for the operation of the equipment which will be tested. This is to be used in case of the necessity of an Emergency Shutdown. • P&ID’s for all equipment to be worked on.

EQUIPMENT / MATERIALS REQUIRED: Personal protective equipment (PPE) as outlined in the PPE Hazard Assessment for Refrigeration Service Technicians. This includes: • Full-Face Respirator – Immediately Available • Chemical Goggles with a Full-Face Shield • Chemical Resistant Apron • Chemical Resistant Gloves • Approved Employee Uniform (i.e. Long Sleeve Shirt / Long Pants) • Safety Toe Shoes or Boots • ARC Flash Apparel (NFPA Requirement)Other Personal Protective Equipment as outlined in the PPE Hazard Assessment

RETA TECHNICAL REPORT PAGE 2

TRANSFER HOSE DIAGRAM

TASK FLOW DIAGRAM

RETA TECHNICAL REPORT PAGE 3

VALVE LEGEND

Task # 1.: Preparing Float Switch Testing

ACTION

COMMENT

1.

Ensure a Maintenance Work Order has been prepared and authorized. If you are a visiting Refrigeration Service Technician, ask your facility contact for all forms and authorization needed for the scope of your work. Verify the location of the float switches to be tested.

Work orders are required for all maintenance activities. Consult your supervisor or facility contact if you have questions.

NOTE: Testing and inspection of level columns and float switches, should only be attempted by operators under the direct personal super- vision of a qualified, experienced, and certified ammonia Refrigeration Service Technician. NOTE: Verify that all safety equipment and PPE is available and functional. Consult your supervisor or facility contact or review the facility Ammonia Refrigeration Compliance Program for this information.

2.

3.

Gather the appropriate tools and PPE.

4.

Gather the appropriate Standard Oper- ating Procedures (SOPs) for the equip- ment you will be working on, and ensure they are readily accessible.

RETA TECHNICAL REPORT PAGE 4

Task # 1.: Preparing Float Switch Testing

ACTION

COMMENT

5.

Ask your supervisor or facility contact to notify all affected departments and per- sonnel including: Facility personnel, con- tractors, and visitors. Prohibit all vehicular and pedestrian traf- fic in the vicinity of operation. Re-familiarize yourself with the location of escape routes, eyewash, and shower stations.

Facility personnel, contractors, and visitors should be trained on the dangers associated with ammonia, including early exposure detec- tion techniques.

6.

NOTE: Portable rinse bottles may be neces- sary depending on the location of the valve control groups. Per the Hazard Assessment for Refrigeration Operators/Technicians. NOTE: If you are using a portable lift, you must have current certification on the type of lift to be used. Perform a ladder inspection after set- up, but prior to use. Do not use facility equip- ment without authorization. Refer to the equipment’s corresponding SOP, your supervisor, or consult your facility contact.

7.

8.

Don required clothing and PPE.

9.

Place ladder (if required) and tie off per OSHA and facility requirements.

10.

Perform visual inspection of the associ- ated portion of the system to determine if the equipment to be tested is currently operational. Perform visual inspection of the associ- ated portion of the system to determine if the liquid levels are normal and the loads on the vessel consistent. Determine the correct testing procedures utilizing the Task Flow Diagram. Continue to the appropriate Task.

11.

It is vital that levels stay consistent during the inspection. As part of the inspection, liquid control will become erratic.

12.

The valve group types covered in this Mainte- nance Procedure are: • Task # 2.a.: Float Switch Testing on Vessels with Drain Valve Configurations • Task # 2.b.: Float Switch Testing on Liquid Make-Up Systems Without a Drain Valve

RETA TECHNICAL REPORT PAGE 5

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

NOTE: Ensure the transfer hose you assem- ble includes a purge/drain valve as shown on the Transfer Hose Diagram on Page 3 of this Maintenance Procedure. CAUTION: Do not proceed to the next step until the transfer hose is fully assembled. Select a source location that has a higher pressure than the vessel being tested. The temperature of the liquid should be equal to or colder than the vessel being tested. An ideal source location (if it is available) is in the outlet of the refrigerant pump with the same suction pressure. NOTE: Be extremely cautious when using High Pressure Liquid (HPL) to fill and test a column on a lower pressure vessel. Because of the difference in pressures and tempera- tures, this process will result in extremely vio- lent boiling of the liquid in the column as the HPL liquid is introduced. For the rest of this procedure, this valve will be referenced as the “Source Valve.”

1.

Assemble the transfer hose. Ensure hose length is appropriate. Note that a short hose may lead to an inability to make proper connections and/or stress the hose fitting. A long hose will increase pumpout time and may lead to excessive refrigerant loss.

2.

Select an appropriate liquid source.

3.

Verify the selected Source Valve is closed. If the selected Source Valve is open, close it. Remove the plug or gauge from the Source Valve.

4.

RETA TECHNICAL REPORT PAGE 6

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

NOTE: Connection “I” is the liquid inlet end of the transfer hose. NOTE: The connection type may be depen- dent on the Source Valve (hose, pipe, nipple, etc.) Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions. NOTE: Valve “Y” is the purge/drain valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions. NOTE: Valve “Z” is the shut-off valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions. NOTE: Valve “X” is the gauge valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions. NOTE: Connection “P” is the outlet of Valve “Y” (the purge/drain valve) on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions.

5.

Attach Connection “I” on the transfer hose to the Source Valve.

6.

Verify that Valve “Y” on the transfer hose is closed.

7.

Verify that Valve “Z” on the transfer hose is closed.

8.

Verify that Valve “X” on the transfer hose is equipped with an ammonia rated pressure gauge (250 PSIG range) and is open.

9.

Attach an ammonia rated purge hose to Connection “P” on the transfer hose.

RETA TECHNICAL REPORT PAGE 7

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

NOTE: Valve “C” is the purge/drain valve on the level column. NOTE: Valve “C” is the purge/drain valve on the level column. NOTE: Connection “O” is the outlet end of the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions.

10.

Confirm that Valve “C” on the level col- umn is closed. Remove the plug from Valve “C” on the level column. Attach Connection “O” on the transfer hose to Valve “C” on the level column.

11.

12.

13.

Slowly open Valve “C” on the level col- umn. Allow the transfer hose to pressurize. Slowly close Valve “C” on the level col- umn. Confirm that the pressure as observed on the gauge attached to Valve “X” is less than the pressure from the Source Valve’s equipment. If a small ammonia leak is observed, the source of the leak should be in- vestigated and the leak repaired. If a large leak occurs, abort the op- eration and contact your supervisor or facility contact. When the leak check has been satisfac- torily completed, continue as follows: Check for ammonia odor.

14. 15.

16.

The Source Valve’s equipment pressure may be observed if a gauge valve is present on the discharge of the equipment. Consult your supervisor, facility contact, or the equipment’s correspond SOP if you have any questions.

17.

RETA TECHNICAL REPORT PAGE 8

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

18.

Slowly close and tag Valve “B” on the level column.

19. 20.

Open the Source Valve.

Check for ammonia odor.

If a small ammonia leak is observed, the source of the leak should be in- vestigated and the leak repaired. If a large leak occurs, abort the op- eration and contact your supervisor or facility contact. When the leak check has been satisfac- torily completed, continue as follows:

NOTE: Valve “Z” is the shut-off valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions.

21.

Slowly open Valve “Z.”

22.

Slowly open Valve “C.”

23.

Ammonia liquid will begin to flow from the Source Valve into the level column. Moni- tor the liquid level in the column.

Control the speed with which the liquid am- monia fills. As the level approaches the float switch level, slow the fill rate.

RETA TECHNICAL REPORT PAGE 9

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

24.

Observe the following positions of the float switch magnets in relation to the at- tractor rod inside the hermetically sealed switches: · As the level of ammonia in the float column rises, the magnet should press against the attractor rod to make the float switch’s High Level Alarm (HLA) initiate an alarm. · As the level of ammonia in the level column rises, the magnet should press against the attractor rod to make the float switch’s High Level Shut Down (HLSD) trip, shutting down the associated compressors within the engine room. · If there is a level probe present, verify the calibration of the level probe. When the liquid level is above the float switch position and the float switch has been determined to be working or in need of replacement, continue to the next step.

The High Level Alarm must activate an audible alarm inside the engine room.

All compressors attached directly to the suc- tion of the tested vessel must shutdown or alarm. If they do not, consult your supervi- sor or facility contact to determine the proper course of action.

If the test determines faulty equipment, con- sider performing level probe calibration at this time.

25.

Slowly close the Source Valve.

RETA TECHNICAL REPORT PAGE 10

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

CAUTION: Failure to properly secure the end of the purge hose in a water container can lead to the hose coming free, whipping around, and possibly causing injury to personnel nearby, as well as allowing ammonia vapor to escape to the atmosphere directly. NOTE: A second barrel of water may become necessary should the first barrel become satu- rated with ammonia. CAUTION: The transfer hose will contain am- monia liquid. Exercise extreme caution. NOTE: Valve “Y” is the purge/drain valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure. CAUTION: Opening Valve “Y” on the transfer hose too fast or too far can cause ammonia and oil to splatter from the barrel of water. NOTE: Valve “X” is the gauge valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure. NOTE: Valve “Y” is the purge/drain valve on the transfer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure.

26.

Terminate and physically secure the purge hose attached to Connection “P” on the transfer hose in a barrel of water.

27. 28.

Slowly close Valve “C.”

Slowly throttle open Valve “Y” on the transfer hose.

29.

After all pressure is bled off, as evi- denced by a pressure reading of less than 2 pounds on the gauge installed in Valve “X” and a lack of bubbles in the wa- ter, continue. Close Valve “Y” on the transfer hose.

30.

RETA TECHNICAL REPORT PAGE 11

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

NOTE: Connection “P” is the outlet of the Valve “Y” (the purge/drain valve) on the trans- fer hose. Refer to the Transfer Hose Diagram on Page 3 of this Maintenance Procedure if you have any questions. Remove the transfer hose from the Source Valve. Reinstall the plug into the Source Valve. Reinstall the plug into Valve “C” on the level column. Observe the liquid level. If there is a level probe, verify the reading when the liquid level reaches a minimum. Consult your supervisor, facility contact, or the facility’s Ammonia Refrigeration Compliance Program for policies regarding the disposal of this barrel.

31.

Remove the purge hose from Connection “P” on the transfer hose.

32.

Remove the transfer hose from Valve “C” on the level column. Remove the transfer hose from the Source Valve. Reinstall the plug into the Source Valve. Reinstall the plug into Valve “C” on the level column. Remove the tag and slowly open Valve “B” on the level column. Reset alarms and utilize the reset to re- start the refrigeration system if required. The barrel utilized for water purging now contains a fluid with water, some ammo- nia, and oil. Typically, containers used for water purging are relocated outside of the engine room and allowed to off gas for a minimum of 24 hours.

33.

34. 35.

36.

37.

38.

RETA TECHNICAL REPORT PAGE 12

Task # 2.a.: Performing Float Switch Testing on Vessels with Drain Valve Configurations

ACTION

COMMENT

39.

Repeat this Maintenance Procedure for each float switch with a drain valve con- figuration, starting with Task # 1 “Prepar- ing for Float Switch Testing.” If this is the last float switch to be tested today, cleanup your work area. Secure your equipment and prepare to document your work. Continue to Task # 3 “Documenting Float Switch Testing.”

See Task # 1 of this Maintenance Procedure.

40.

See Task # 3 of this Maintenance Procedure.

RETA TECHNICAL REPORT PAGE 13

Task # 2.b.: Performing Float Switch Testing on Liquid Make-Up Systems With- out a Drain Valve

ACTION

COMMENT

NOTE: Testing may take a significant amount of time to perform. Plan accordingly.

1.

This procedure will fill the Primary Vessel with liquid to the level of the tested float switch. Because of the amount of liquid required to fill the target vessel, verify that sufficient liquid ammonia is present in the Primary Vessel. There may not be enough pressure to move ammonia liquid into the target ves- sel and an ammonia transfer pump may need to be utilized. Shut down associated compressors us- ing a “Normal Shutdown.” Do not turn off the controls for the compressors.

This will require a special procedure. See your supervisor or facility contact.

2.

Refer to the corresponding SOP for each com- pressor. NOTE: This includes both compressors draw- ing vapor from or discharging vapor to this vessel. This may be a transfer solenoid, transfer pump, or transfer vessel. Consult your facility contact if you have any questions. Monitor the liquid level in the Primary Vessel during this operation. Verify that it does not fall below the minimum fill line. NOTE: During this operation, the pressure in the target vessel will rise significantly as there are no compressors drawing on this vessel.

3.

If installed, shut down and isolate the transfer system.

4.

Change the liquid make-up solenoid to the manual open position. If an electronic expansion valve is being utilized, manually open it.

5.

Ammonia liquid will fill the ammonia line piping and into the float switch column being tested.

RETA TECHNICAL REPORT PAGE 14

Task # 2.b.: Performing Float Switch Testing on Liquid Make-Up Systems With- out a Drain Valve

ACTION

COMMENT

6.

Observe the following positions of the float switch magnets in relation to the at- tractor rod inside the hermetically sealed switches: · As the level of ammonia in the float column rises, the magnet should press against the attractor rod to make the float switch’s High Level Alarm (HLA) initiate an alarm. · As the level of ammonia in the level column rises, the magnet should press against the attractor rod to make the float switch’s High Level Shut Down (HLSD) trip, sending a Shut Down signal to all associat- ed compressors within the engine room. · If there is a level probe present, verify the calibration of the level probe. When the liquid level is above the float switch position and the float switch has been determined to be working or in need of replacement, continue to the next step. Change the liquid make-up solenoid or the electronic expansion valve back to the automatic position.

The High Level Alarm must activate an audible alarm inside the engine room.

All compressors attached directly to the suc- tion of the tested vessel must shutdown or alarm. If they do not, consult your supervi- sor or facility contact to determine the proper course of action.

If the test determines faulty equipment, con- sider performing level probe calibration at this time.

7.

RETA TECHNICAL REPORT PAGE 15

Task # 2.b.: Performing Float Switch Testing on Liquid Make-Up Systems With- out a Drain Valve

ACTION

COMMENT

NOTE: Because all compressors associated with the target vessel were stopped, the trans- fer system may not be successful at transfer- ring liquid. NOTE: Compressors should NOT restart au- tomatically without a reset signal. Silence alarms and reset shutdown condition by using the appropriate SOP for the affected equipment. Refer to the SOP ORSO (Overall Refrigeration System Operation) for a list of equipment SOP’s available.

8.

Turn on and remove the isolation from the transfer system if one is equipped.

9.

Reset the alarms and utilize the reset to restart the refrigeration system if re- quired. Do NOT restart the compressors at this time.

10. Check the ammonia level in level column. Verify that the level in the vessel is below the high level shutdown level.

RETA TECHNICAL REPORT PAGE 16

Task # 2.b.: Performing Float Switch Testing on Liquid Make-Up Systems With- out a Drain Valve

ACTION

COMMENT

11.

· Carefully restart the smallest com- pressor that takes suction from the target vessel. · Set the slide valve (Capacity Con- trol) to the minimum position. This should read 10% or below. · Close the suction valve on the com- pressor. · Crack the suction valve open ap- proximately 1/8 of a turn. Monitor the suction pressure shown on the compressor suction gauge. Aim to keep the compressor running, but at the lowest possible pressure above the low-pressure cutout. · Monitor the suction temperature. It should stay about 15 to 20 degrees above the equivalent saturated suction pressure / temperature. · Check ammonia level in level col- umn. When the level in the vessel is below the High Level Shutdown level, slowly open the suction on the compressor. Continue to monitor the suction tempera- ture. It should be at least 3 to 5 degrees above the equivalent saturated suction pressure / temperature.

CAUTION: Monitor the compressor discharge temperature. In the event of a rapid drop in discharge temperature, initiate an emergency stop immediately.

RETA TECHNICAL REPORT PAGE 17

Task # 2.b.: Performing Float Switch Testing on Liquid Make-Up Systems With- out a Drain Valve

ACTION

COMMENT

12.

Re-start the associated compressors one at a time to prevent the suction pressure from falling too quickly. Verify that the suction piping is clear and free of liquid. Verify all portions of the refrigeration sys- tem are operational. Re-start associated compressors that were turned off in steps above. Repeat this Maintenance Procedure for each float switch that has a liquid make- up system without a drain valve configu- ration, starting with Task # 1 “Preparing for Float Switch Testing.” If this is the last float switch to be tested today, cleanup your work area. Secure your equipment and prepare to document your work. Continue to Task # 3 “Documenting Float Switch Testing.”

Refer to the corresponding SOP for each com- pressor.

13.

14.

Refer to the corresponding SOP for each com- pressor.

15.

See Task # 1 of this Maintenance Procedure.

16.

See Task # 3 of this Maintenance Procedure.

RETA TECHNICAL REPORT PAGE 18

Task # 3.: Documenting Float Switch Testing

ACTION

COMMENT

NOTE: Typically, the facility contact will select a member of the facility’s team to transfer the deficiencies found during the Annual Ammo- nia Inspection to the facility Deficiency Follow- Up Log.

1.

The ammonia Refrigeration Service Technician who conducted the work shall draft a summary letter listing all of the de- ficiencies discovered during the testing. The ammonia Refrigeration Service Technician who conducted the work shall sign and date the summary. The Maintenance Supervisor or facility contact will prepare maintenance repair orders for any repairs identified during the testing. The supervisor or facility contact will se- lect a member of the facility’s team to prepare maintenance repair orders for any equipment repairs identified during the inspection. Typically, the supervisor or facility contact will also prepare Management of Change Forms for equipment repairs identified during the testing, as well as for changes to equipment information. Continue to Task # 4 “Concluding Float Switch Testing.”

2.

3.

NOTE: In some instances, the supervisor or facility contact may request that you prepare the Management of Change Forms.

4.

5.

See Task # 4 of this Maintenance Procedure.

RETA TECHNICAL REPORT PAGE 19

Task # 4.: Concluding Float Switch Testing

STEP ACTION

COMMENT

1.

Restore allowable vehicular and pe- destrian traffic in your work area. Complete an entry in the facility Mas- ter Maintenance Log (or facility equiv- alent), noting the work performed. If a system upset occurred, record the details of the event in the Master Main- tenance Log (or facility equivalent). Note if the system was restored to full functionality, and if it was not, explain why in detail. Complete any permits or paperwork required. Return any facility owned documents, such as Standard Operating Proce- dures (SOP’s) and P&ID’s. If appropriate, debrief with your super- visor or facility contact: • Inform your contact of the sta- tus of the project. • Inform your contact of any is- sues which may require cor- rection. Remove PPE, clean, perform any re- quired preventive maintenance, and stow. Secure all tools and equipment uti- lized.

2.

If there is not an established Master Mainte- nance Log (or facility equivalent), log the infor- mation on your work order. This includes the shutting down of equipment or any instance where the system is not left in complete functioning condition.

3.

4.

5.

6.

7.

8.

RETA TECHNICAL REPORT PAGE 20

THE

TECHNICAL

REPORT

The Technical Report is an official publication of the Refrigerating Engineers & Technicians Association (RETA). RETA is an international not-for-profit association whose mission is to enhance the professional development of industrial refrigeration operating and technical engineers. Don Chason Executive Editor Jim Barron Executive Director

704-455-3551 Sara Louber Senior Director, Office Operations sara@reta.com

jim@reta.com Dan Reisinger Certification Manager

dan@reta.com Dan Denton

Michelle Robinson Conference Manager michelle@reta.com Vince Grindel Education Coordinator vince@reta.com

Chapter Relations ddenton@reta.com

The information in this publication is based on the collective experience of industry engineers and technicians. Although the information is intended to be comprehensive and thorough, it is subject to change based on particular applications, field experience, and technological developments. The Refrigerating Engineers & Technicians Association expressly disclaims any warranty of fitness for a particular application, as well as all claims for compensatory, consequential, or other damages arising out of or related to the uses

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RETA TECHNICAL REPORT PAGE 21