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To Pull or Not to Pull a Vacuum

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#21 ·
jactechcool said:
Im new at this, but one thing that was clear over and over again in class, ALWAYS pull a vacuum if you open the system and ALWAYS flow nitrogen when brazing.

Talked to a friend who is a tech for 4 years. Asked him if he flows nitrogen...he is like "What?". I explain. He is like "no, never".

--John
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Its a sad reality that many techs don't do these things.

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#22 ·
rwbil said:
Trying to be a better tech, but don't want to wasted time not needed to be wasted. Normally I do not pull a vacuum for quick changes.

What rules do you use to decide if you need to pull a vacuum or not. Or maybe you modify the rules based on the situation.

For example, if the system is only open for a short period, let's say you unclog or change a piston, would you pull a vacuum down to 250 microns or modify your vacuum rules.
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EPA 608, Service Practice Requirements, 1st item states when opening a system evacuation and recovery of refrigerant is a requirement. Anything else goes under the heading "don't ask, don't tell", or "you have the right to remain silent". Since 1993.

To prevent contamination you would have to intentionally vent (purge) refrigerant while the circuit was open.
 
#23 ·
ehsx said:
EPA 608, Service Practice Requirements, 1st item states when opening a system evacuation and recovery of refrigerant is a requirement. Anything else goes under the heading "don't ask, don't tell", or "you have the right to remain silent". Since 1993.

To prevent contamination you would have to intentionally vent (purge) refrigerant while the circuit was open.
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One would only have to vent a deminimus amount.


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#24 ·
I usually work on large HVAC and refrigeration systems, but the same rules apply to resi. If refrigerant is off gassing out of the system then no vacuum needed. If I have to braze, then always pull a vacuum. Look at the situation logically. Are you opening a small line or a high point for a few minutes? Is the volume large enough that refrigerant will keep boiling out? Does it look like air might be able to get in? If it looks like a little air might get in, and it’s not very humid, then I pull a quick vacuum. No micron gauge. If the system is already dry, why would I worry about pulling a 500 micron vacuum if only a small amount of dry air or nitrogen entered the system? I’d just be waiting for all the residual refrigerant to boil out. If I’m doing something major like a compressor change out on a split or package unit, then it gets a deep vacuum.
 
#25 ·
Red Man said:
I usually work on large HVAC and refrigeration systems, but the same rules apply to resi. If refrigerant is off gassing out of the system then no vacuum needed. If I have to braze, then always pull a vacuum. Look at the situation logically. Are you opening a small line or a high point for a few minutes? Is the volume large enough that refrigerant will keep boiling out? Does it look like air might be able to get in? If it looks like a little air might get in, and it’s not very humid, then I pull a quick vacuum. No micron gauge. If the system is already dry, why would I worry about pulling a 500 micron vacuum if only a small amount of dry air or nitrogen entered the system? I’d just be waiting for all the residual refrigerant to boil out. If I’m doing something major like a compressor change out on a split or package unit, then it gets a deep vacuum.
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Off gassing is not considered deminimus release. Since mid 90's, oil can not be removed from a pressurized system to an open container. Also there have been a number of updates to 608 since implementation, most recent in the last couple of years.

EPA regulations (40 CFR Part 82, Subpart F) under Section 608 of the Clean Air Act prohibit individuals from intentionally venting ozone-depleting substances (ODS) or their substitutes while maintaining, servicing, repairing, or disposing of air-conditioning or refrigeration equipment. Only three types of releases are permitted:

"De minimis" quantities of refrigerant released while making good faith attempts to recapture and recycle or safely dispose of refrigerant including releases that occur when connecting or disconnecting hoses to charge or service appliances.
Refrigerant emitted during the normal operation of air-conditioning and refrigeration equipment (as opposed to during the maintenance, servicing, repair, or disposal of this equipment), such as from mechanical purging and leaks. However, EPA requires that leaks above a certain size be repaired in equipment that contains 50 pounds of refrigerant or more.
Releases of substitute refrigerants that EPA has determined do not pose a threat to the environment. See the Recent Regulatory Developments box for more information.
 
#26 ·
ehsx said:
Off gassing is not considered deminimus release. Since mid 90's, oil can not be removed from a pressurized system to an open container. Also there have been a number of updates to 608 since implementation, most recent in the last couple of years.

EPA regulations (40 CFR Part 82, Subpart F) under Section 608 of the Clean Air Act prohibit individuals from intentionally venting ozone-depleting substances (ODS) or their substitutes while maintaining, servicing, repairing, or disposing of air-conditioning or refrigeration equipment. Only three types of releases are permitted:

"De minimis" quantities of refrigerant released while making good faith attempts to recapture and recycle or safely dispose of refrigerant including releases that occur when connecting or disconnecting hoses to charge or service appliances.
Refrigerant emitted during the normal operation of air-conditioning and refrigeration equipment (as opposed to during the maintenance, servicing, repair, or disposal of this equipment), such as from mechanical purging and leaks. However, EPA requires that leaks above a certain size be repaired in equipment that contains 50 pounds of refrigerant or more.
Releases of substitute refrigerants that EPA has determined do not pose a threat to the environment. See the Recent Regulatory Developments box for more information.
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Hes not talking about recovery. He's talking about running a vacuum after a repair.

As in, pump a unit back into itself, fix a leak, and open the valves back up.
 
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#28 ·
I do a lot of old refrigeration for supermarket, if I’m changing out an old pressure control, I pump it down and leave a small positive pressure on it and swap and go. If you actually open it to atmosphere and it can suck in! Well all bets are off.
 
#29 ·
Rhinohead said:
I do a lot of old refrigeration for supermarket, if I’m changing out an old pressure control, I pump it down and leave a small positive pressure on it and swap and go. If you actually open it to atmosphere and it can suck in! Well all bets are off.
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Just saying sometimes best not to ask or tell, but some carry it way to far.
 
#31 ·
ehsx said:
Opening requires recovery. Cannot achieve EPA requirements by internal system pumpdown.
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Wait, what? Are you saying that even if you are able to achieve zero psi on both the suction and liquid lines by doing a standard "internal system pumpdown", you are still required to hook up a recovery machine in order to "recover" an amount of refrigerant that wouldn't even be detectable on your scale?

Does the EPA require the recovery machine to be plugged in and turned on? Would hooking it up and then going "yep, gauge is at zero, must be done" be good enough? Is this how you do it?
 
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#32 ·
ammoniadog said:
Wait, what? Are you saying that even if you are able to achieve zero psi on both the suction and liquid lines by doing a standard "internal system pumpdown", you are still required to hook up a recovery machine and "recover" an amount of refrigerant that wouldn't even be detectable on your scale?

Does the EPA require you to actually plug the recovery machine in and turn it on? Would hooking the thing up and then going "yep, gauge is at zero, must be done" be good enough? Is this how you do it?
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The EPA actually has various levels of vacuum requirements for recovery. Zero isn't good enough unless the system is leaking.
Fortunately I never get to work on a non-leaking system.
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"Is this before or after you fired the parts cannon at it?" - senior tech
 
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#33 ·
ammoniadog said:
Wait, what? Are you saying that even if you are able to achieve zero psi on both the suction and liquid lines by doing a standard "internal system pumpdown", you are still required to hook up a recovery machine in order to "recover" an amount of refrigerant that wouldn't even be detectable on your scale?

Does the EPA require the recovery machine to be plugged in and turned on? Would hooking it up and then going "yep, gauge is at zero, must be done" be good enough? Is this how you do it?
Click to expand...
refrigerant dependent based on table.

View attachment EPAs_Evacuation_Level_Chart.pdf
 
#35 ·
ehsx said:
Off gassing is not considered deminimus release. Since mid 90's, oil can not be removed from a pressurized system to an open container. Also there have been a number of updates to 608 since implementation, most recent in the last couple of years.

EPA regulations (40 CFR Part 82, Subpart F) under Section 608 of the Clean Air Act prohibit individuals from intentionally venting ozone-depleting substances (ODS) or their substitutes while maintaining, servicing, repairing, or disposing of air-conditioning or refrigeration equipment. Only three types of releases are permitted:

"De minimis" quantities of refrigerant released while making good faith attempts to recapture and recycle or safely dispose of refrigerant including releases that occur when connecting or disconnecting hoses to charge or service appliances.
Refrigerant emitted during the normal operation of air-conditioning and refrigeration equipment (as opposed to during the maintenance, servicing, repair, or disposal of this equipment), such as from mechanical purging and leaks. However, EPA requires that leaks above a certain size be repaired in equipment that contains 50 pounds of refrigerant or more.
Releases of substitute refrigerants that EPA has determined do not pose a threat to the environment. See the Recent Regulatory Developments box for more information.
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So we can’t drain oil into a bucket? That’s news to me. What are we supposed to do with it, fill a recovery cylinder?
 
#36 ·
R600a said:
Honestly on most installs and change outs I'm sent the address that morning and we go install it. When I find the job myself I like to do a load calculation if at all possible.

Sent from the Okie state usin Tapatalk
"Is this before or after you fired the parts cannon at it?" - senior tech
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Yep I used to work for a residential company that close to 1000 installs a year. I’m not aware of any load calculations ever being done.
 
#37 ·
jactechcool said:
Im new at this, but one thing that was clear over and over again in class, ALWAYS pull a vacuum if you open the system and ALWAYS flow nitrogen when brazing.

Talked to a friend who is a tech for 4 years. Asked him if he flows nitrogen...he is like "What?". I explain. He is like "no, never".

--John
Click to expand...
Yep I used to work for a large residential company that did close to 1000 installs a year. I never once saw an installer flow nitrogen. At the time, I asked the main installer there that had been doing it for like 25 years if he flowed nitrogen and he looked dumbfounded and said, “nah I’ve never heard of that”
 
#39 ·
heatingman said:
One would only have to vent a deminimus amount.


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What is the definition of deminimus again, The largest amount you can release without getting caught?

(Dear Mr EPA agent, if you are reading this it is only meant to be a joke!)
 
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