The IOR is often asked for advice on the interpretation of standards and regulations. Questions are responded to by the IOR Technical Committee - a group of members who are experts in various fields within RACHP.  Below are some of our recent Q&A.

Replacement of PRVs

Q. Regarding the requirement to replace PRVs on a four year old system that has double PRVs for each port, as one PRV has not been used on each port would they still need replacing?

A. The answer was “Both PRV’s expire from their original calibration date, therefore both will need re calibrating or replacing. The valve simply allows one to be removed at a time whilst leaving the system protected"

Anhydrous Ammonia water content levels

Q. Our supplier is unable to supply Anhydrous Ammonia to their previous standard of 200ppm water content. Future supplies will be 600ppm, until the processing plant is upgraded.  I'd be grateful if someone could advise if this would be acceptable?

A. The quantity of water that can be tolerated in an ammonia refrigeration system depends on the type of system and the way in which it is operated.  In most cases there will not be a problem with having 600ppm water content in the ammonia that is charged into a system.  It is common practice to ensure that there is a water content of not more than 2,000ppm as a measure of protection against stress corrosion cracking in steel pressure vessels (see for example Annex L of the Institute of Refrigeration’s Safety Code of Practice for use of Ammonia as a Refrigerant).  Particular care will be required to check whether a water content of 600 ppm is acceptable in systems that do not have a receiver in the low pressure side of the system or that operate the evaporators on a DX type of control (where the refrigerant is evaporated to dry gas).  In all other cases having 600ppm in the refrigerant charge will probably have no discernible adverse effect.

Effective Handover of Plant

Q. Is there any guidance on what documentation etc should be included in the handover of new systems between end user and contractor?

A. This IOR Technical Committee article outlines key elements https://ior.org.uk/more-effective-handover-of-plant-to-the-client

Please use the contact form if you have questions you would like answered.  The IOR is not able to comment on specific sites or contractual arrangements but can give generic guidance directing you to relevant content within standards, codes and regulations. 

The Institute of Refrigeration accepts no responsibility for errors and omissions resulting from these comments.