Anhydrous Ammonia Loss

One issue that may come up during an audit is replacement of ammonia.  If you have added ammonia to your refrigeration system someone may ask you:

• Where was the leak?
• Did you report a leak or release of ammonia?
• Why are you adding ammonia, if you do not report a release?

This may put you in an untenable situation with trying to find an explanation for seemingly ordinary maintenance practices.  Where might you find a potential, unnoticed source of ammonia loss?

One area you might consider investigating is the refrigerated purger.   The purpose of the purger is to remove non-condensable gases from the condenser(s) located in the high-side of the refrigeration system.  A refrigerated purger operates on the principle of condensing the ammonia to remove it from the non-condensable gases released through the water bubbler on the purger.

The performance of the purger evaporator is dependent on the suction pressure of the refrigeration system it is connected to.  The saturation temperature of that suction pressure is utilized to condense the ammonia from the non-condensable gases.  This is an important consideration for using the lowest suction pressure available in the refrigeration system.  Lower suction pressures translate into lower saturation temperatures.  This lower saturation temperature becomes the evaporating temperature for the purger evaporator, which allows more ammonia to be condensed from the non-condensable gases.

Therefore, if the purger evaporator surface is not very cold it can only condense ammonia to within that saturation temperature achieved by the available suction pressure.

Any ammonia remaining in the non-condensables will be purged with the non-condensables when they exit the purger.  With the use of the water bubblers to absorb any residual ammonia from the purged gases you may not notice the ammonia loss by smell.  However, over long periods of time the gradual loss of ammonia may become significant enough to warrant adding refrigerant to the system.

If you are using a purger and have unexplained losses of ammonia you may want to look at the refrigerated purger.  This might explain where the ammonia went to.

An auditor may inspect your records and find the addition of ammonia to the system.  If you have not reported this or instituted a program for dealing with this, it may be difficult to explain to the auditor.

Tags: ammonia loss, non-condensable gas, refrigerated purger, release reporting

This entry was posted on Thursday, July 2nd, 2009 at 12:00 pm and is filed under cold storage warehouse, food processing, industrial refrigeration. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.