Why Draining Refrigerant Oil Should be a Regular Maintenance Task and How to Do It Safely

Draining the refrigerant oil from your chiller.

Oil draining is a simple, but very important, maintenance task for your industrial refrigeration system. It should be performed on a regular schedule or as required based on the type of compressors used in the system.  If refrigerant or chiller oil is not drained, it will replace the liquid refrigerant in the evaporator, causing poor temperature or heat transfer. Worst case scenario, not draining the oil can cause your entire chilling system to shut down.

Where Does the Refrigerant Oil Drain?

Where the refrigerant oil drains from depends on the type of industrial refrigeration system you have. Chiller oil should never be removed directly from the refrigeration system or from the high-pressure receiver. Instead, draining from an oil pot or oil still is the best approach. This helps eliminate the risk of opening the system to the atmosphere and potentially pouring liquid refrigerant into an enclosed space, the engine room or the refrigerated space. It also prevents refrigerant from combining with the oil and complicating the draining process.

Make sure you understand the basics of refrigeration and how your chilling system works before attempting to drain oil or any other maintenance task.

How to Safely Drain Refrigerant Oil

Oil draining is a straight forward part of industrial refrigeration maintenance, but ranks high in industry accidents due to the amount of times it is performed. Safety should always be your priority.

Follow these best practices to prevent possible issues and minimize risk:

  1. Oil draining is a long, slow process. The procedure should be scheduled for times when the facility is not in use or occupied by patrons. Always allow suitable time to complete the task.
  2. Keep a log of the quantity of refrigerant oil drained and added to the system.
  3. Wear personal protective equipment (PPE) while completing the oil draining procedure to protect your respiratory system, skin and eyes.
  4. Always have a second person nearby observing and prepared to give assistance in the oil draining procedure.
  5. Never open an ‘oil out’ valve more than one turn without a quick or self-closing valve in line.
  6. Use a ball (1/4 turn, closing) valve or self-closing valve as a safety, downstream from the main oil-out valve.
  7. Always drain oil pots or oil stills 5-10 feet away from the oil-out valve.
  8. Never leave an oil draining process unattended.
  9. All oil pots or oil stills should have a safety relief valve installed.
  10. Develop an emergency response plan with instructions, contact names, addresses and phone numbers and post it in an obvious location.

How Industrial Refrigeration Contractors Can Help

Each chilling system has its own unique operating and installation characteristics and site-specific procedures. Our licensed Refrigeration Technicians can train your team in proper processes for adding and draining oil, as well as writing standard operating procedures to keep on-site.

Industrial Refrigerated Systems is a Berg Company. If you would like more information on how to service your industrial refrigeration system or to schedule a chiller maintenance and cleaning appointment for your system, contact us.