View Full Version : Purge or vac?

07-08-2012, 10:05 AM
Just trying to get an idea on what is standard accross the world. I remember Sabroe videos where they recommend purging compressors after servicing. does anyone do this? or are you strict with n2 pressure test and ,<200 micron evacs ?

07-08-2012, 10:56 PM
Purging is a dirty word now-a-days. :)

monkey spanners
08-08-2012, 12:21 AM
Would think even with NH3 a vac would be best, can see how you could purge a pipe and it push all the air out but with a compressor there will be dead areas that never got the air pushed out imo. (don't work on ammonia so...)

08-08-2012, 08:01 AM
If we were in a perfect world you would use a vac pump, each scenario can be different.
If plant has an air purger, I would not worry to much, but if a vac pump was available I would use it.

Plants with no air purger or PHE as condenser etc you definately have to use a vac pump.

It is necassary to protect the environment so ammonia in water should be disposed of in the correct way, not down the drain etc.

09-08-2012, 04:00 AM
At our plant we use a vac anytime after we open up the system. We also have an auto purger.

I'm curious though Ranger what is the correct way to dispose of ammonia in water? I'm new to NH3. When we take down say an evap to change out a solenoid we isolate the unit, purge out the ammonia into a bucket of water, let that bucket sit on the roof for several days to a week then we just dump it out. It just runs down the gutters and into the sewer. Should we be doing something else with our saturated water?

09-08-2012, 07:02 AM
Yeah KY_ICE the right thing to do is neutralize the solution with acid and dispose, or easier and a good sale to customers is send to a waste disposal company.
Ranger i agree some what, not every situation is "vac pump compatible" i would use 90% of the time. Trouble is vac pumps take quite a beating unless you change the oil religiously. I now use a venturi, they will pull down to -90 kPa, you can buy them through, https://www.facebook.com/AmmoniaNZ?ref=hl, obviously they dont remove moisture unless you leave them on for awhile, but as for air they are primo.

09-08-2012, 07:16 AM
Hi NH 4 life.
who lives in the perfect world when client is beating on you to get machine going. To quote the Kirby manual "a good purge is not good enough ". Me a purge into a bucket of water and after the bubbles stop it is back on line.

10-08-2012, 04:42 PM
Sometimes after vacuuming mech seal start leaking. I prefer purging.

10-08-2012, 06:53 PM
Purge the surplus ammonia vapour through water.
Once bubbles almost disappeared remove vent line from water and allow system to breathe. As an extra precaution I will If I feel it is necessary then pull a vacuum on that isolated part of the system, prior to opening it up.
I tend to do all this outside and remote of the plant room. Using Hydraulic fittings (compatible with the relevant model of compressor) and 6mm quick release Pneumatic fittings.
A nice long length of 6mm plastic pneumatic line takes all the hassle of alarm isolation and activation away.
So no unplanned visits from the local fire brigade either.
And before anyone starts quoting the tree huggers manual. Ammonia is a totally natural substance and if allowed to slowly vent to atmosphere will cause no harm at all.
A saturated Ammonia solution will slowly loose its ammonia content to atmosphere.

Obviously if poured into a watercourse or allowed to vent off with the wind in the wrong direction. Then the responsible idiot should be stuffed. I have when deemed necessary purged quite large amounts of Ammonia through water and then controlled the evaporation of both the water and the ammonia it contains.
Ammonia only hurts anything or anyone when not treated with the respect it deserves.

If the water into which you are purging starts releasing ammonia from its surface.
Stop and change to a fresh source of water that way you will never end up with a saturated solution that cannot
over a relatively short space of time return to water and the ammonia dissipated into the atmosphere.
A truely saturated solution turns white (seen as a milky cloud) as the Ammonia content increases.
It ain't rocket science guys and a lot less hassle than propane and other volatile substances that the tree huggers
have yet to think they know something about!
Purging and vacuuming are valuable tools in the fridgies toolbox.
The idea of a saturated solution scares the hell out of me and rightly has strict guidelines on it's handling and disposal!
The fact that it is regulated is a sad endorsement on the lack of training out there.
Don't create it and you don't has a problem!

10-08-2012, 08:45 PM
We do all above, or did.
We have a few numbnuts who pour it down the wrong drain, then client or authorities goes berzerk.
We all then pay the price. you can't do this & that etc etc.
We tried nuetralizing some water on a bigger job with citric acid, that was not practically achievable.
Sent it to Orica, no worries $3-4k later.
Then the brain washing set in for the younger guys of our organization.

Venturi is great to, but theoretically can't use thar either.

It used to be good to let a bit of ammonia go to get rid of the pests around plant rooms, now were told to wear a monitor so we know its there & don't breath to much!