purging and pressuring ac with n2

[kefah]

hi every one
i want to use n2 in purging and testing ac for leaks
and first time to me
my q are
1_ what precautions i must make in care when use n2 in purging etc....
2_ which type of n2 i must use
because in iraq we have pure n2 only but some experts adviced me to use impure n2 cylinder which contain 90% n2 and 10% oil because its best than pure n2 in purging and testing

[install monkey]

oxygen free nitrogen, u need a regulator- rated for 50 bar - test r22 systems to 20 bar and 410a systems at 40 bar
only use in well ventilated areas
leak test using leak detector spray- not soapy water

[The Viking]

-Only use pure N2, also known as OFN (Any oils will contaminate the system and any O2 will give soot in the pipes when you braze)
-There are 2 different types of regulators, one that regulates on flow and one that regulate on pressure. Ideally you would have one of each but most engineers get by with just one that regulates on pressure. NEVER use one that regulates on flow for pressure testing.
-Make sure you got good quality hoses and a good manifold or test rig between your regulator and the system. Ideally you would have a test rig with a decent gauge and 2 pressure relief valves but few engineers does (As a result of not having this some engineers are injured or even killed each year)
-Always make sure that your regulator is set to it's minimum setting (=No flow=0) before you open up the cylinder valve and only slowly increase the pressure afterwards,
-When you use it for purging whilst brazing, to prevent soot from forming inside the pipes, you want a slow steady flow to disperse the air but not a lot of pressure.
-When you pressure test, slowly bring the pressure up to a couple of Bars then stop and see if there is any rapid pressure drop then slowly increase the pressure to ~10 Bar and again check for pressure drop. (this will save a lot of OFN if there is a leak)


NOTE: LEAVE ANY VALVES ON YOUR TEST RIG / MANIFOLD FULLY OPEN WHILST YOU ARE ADDING OFN TO THE SYSTEM, ONLY USE THE OFN REGULATOR TO ALTER OR STOP THE OFN FLOW!
After you reached the desired pressure / not need to purge any more, shut off the flow on the regulator and only after this been done shut the valves on manifold or rig.

Welcome to the future!
:cool:

.

[kefah]

thank u both
The Viking
install monkey
those info was very useful to me
i appreciate that from you
now my question
can i use the same type oxygen regulator for n2 cylinder
also the same r22 manifold gauge type
and what are the max pressure i must give when testing for leaks
for 2 ton split unit and 4 ton 5 ton ac

[The Viking]

No, not the same regulator.

The pressure depend on what leak you are looking for...

A big leak will be easy to find even at low pressures but a small leak on the high pressure side will require a higher test pressure.
At no point should you pressurise the system above the pressure the manufacturer has given as Maximum Test Pressure. Normally no pressure test for leaks should be above 1.1 x MOP whilst strength tests can be 1.3 x MOP. (But never above the maximum test pressure)

:cool:

.

[kefah]

im use this type regulator with o2
cylinder
10052
so i meant not use the same regulator
but use another regulator from same type is that possible

[kefah]

As a result of not having this some engineers are injured or even killed each year
can you explain

[install monkey]

http://en.wikipedia.org/wiki/Inert_gas_asphyxiation

http://books.google.co.uk/books?id=gniJE5lK0YAC&pg=PA524&lpg=PA524&dq=pressure+testing+air+conditioning&source=bl&ots=Bi2qyAxRYW&sig=8_lnYjcKUCOdIpVxDmJiNGeKW34&hl=en&sa=X&ei=984fUfTzA4SE4gTaqYDACw&ved=0CHgQ6AEwBg#v=onepage&q=pressure%20testing%20air%20conditioning&f=false

[kefah]

http://en.wikipedia.org/wiki/Inert_gas_asphyxiation

http://books.google.co.uk/books?id=gniJE5lK0YAC&pg=PA524&lpg=PA524&dq=pressure+testing+air+conditioning&source=bl&ots=Bi2qyAxRYW&sig=8_lnYjcKUCOdIpVxDmJiNGeKW34&hl=en&sa=X&ei=984fUfTzA4SE4gTaqYDACw&ved=0CHgQ6AEwBg#v=onepage&q=pressure%20testing%20air%20conditioning&f=falsethank u
but what about
http://www.refrigeration-engineer.com/forums/showthread.php?38190-purging-and-pressuring-ac-with-n2&p=273386#post273386

[install monkey]

needs to be a nitrogen gauge rated for 50 bar-for 410a systems
also a flow regulator to use for brazing pipework

[kefah]

i want the nitrogen for 22 ***** system and 407c
because it only success-ed in Iraq
and 410 a is failed

[install monkey]

u still need to pressure test to over 20bar so u need a suitable regulator, connect ur gauges to the regulator to accuratly see the system pressure so you can moniter if any pressure drop

[kefah]

u still need to pressure test to over 20bar so u need a suitable regulator

http://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=10052&d=1360613630
this regulator is 25 bar max pressure
can i use it with n2 or not

[install monkey]

cant tell from the picture- if it says nitrogen then yes-if oxygen then no

[kefah]

ok
what if i use co2 gas instead of nitrogen
what are the advantages
and disadvantages

[install monkey]

co2 is an inert gas but go with the cheapest, u can use helium to find small leaks (mixed with oxygen free nitrogen) no mention of co2- http://www.refrigeration-engineer.com/forums/showthread.php?36961-system-pressure-testing
http://www.refrigeration-engineer.com/forums/showthread.php?35606-ref-question&highlight=c02+pressure+test

[kefah]

thank you install monkey
you really helped me