Refrigeration Vacuum Pumps

How important is proper evacuation?
Evacuating a system before charging serves two purposes. The obvious one is that of removing air from the system. The other, equally important, is the removal of moisture. For a refrigeration or air conditioning system to function properly, both air and moisture must be removed. What happens if you don't?

Problems resulting from air in a system

	Increased high-side and low-side pressure
	Increased energy consumption
	Unable to achieve low temperature
	Trips high-pressure safety cut-out

Problems resulting from moisture in a system

	Blocked expansion valve/cap tube
	Acid formation in refrigerant oil
	Premature compressor bearing failure
	Winding burnout in hermetic compressors

How long do I need to evacuate?
If you are using a vacuum pump in excellent condition and new oil (very important), then you can probably remove virtually all of the air in the system in about 5-15 minutes. However, moisture takes MUCH longer. The fact is that most people (including service professionals) do not evacuate systems long enough to remove all of the moisture. The length of time required to remove moisture depends of the quality of your vacuum pump and the temperature of the system at the time of evacuation. Use the the table below as a guide if you are using a new high-quality vacuum pump. (note: The "temperature" represents the coldest part of the system).

Temperature	Minimum Time
90^o F / 32⁰ C	1 Hour
80^o F / 27⁰ C	2 Hours
75^o F / 24⁰ C	3 Hours
70^o F / 21⁰ C	4 Hours
65^o F / 18⁰ C	8 Hours
60^o F / 15⁰ C	36 Hours
55^o F / 13⁰ C	50 Hours
50^o F / 10⁰ C	72 Hours

My vacuum pump pulls down to 30", is that good enough?
To start off with, you need to recognize that no standard refrigeration gauge set is accurate enough at low vacuum levels to give you much useful information at all. For example, I can assure you that your pump does not pull down to 30". I know your gauge may say 30" but a perfect vacuum (unattainable on earth) is 29.92". That may sound close enough until you realize that you can't remove all the moisture until the vacuum level gets down to 29.72" (5,000 microns) or lower. If we assume that your gauge set is off by only .5 psi (equal to 1" of mercury) then when it reads 30" it is actually at 29.00" or nearly 5x higher pressure than the vacuum level required to dehydrate your system.

If I can't use my gauge set, what am I supposed to do?
Both the 1.5 and 4.0 cfm pumps incorporate a built-in mechanical vacuum gauge which reads between 29" and 30" of vacuum. While not a perfect measure, this will at least let you know if your pump is "in-the-ball park". The best practical way to ensure that you are evacuating low enough to completely remove moisture is to make sure your vacuum pump is a two-stage type, in excellent condition and filled with new, clean oil at least every 10 hours of operation.

1.5 cfm Precision Two-Stage Vacuum Pump

This high-performance pump is perfect for boaters and anyone else needing maximum performance in a small, portable package. The 1/6 HP, 115v motor allows the pump to be easily run from shore power, generators or most 800w+ inverters. The precision two-stage pump chamber achieves vacuum levels which are among the lowest in the industry.

	Suitable for systems up to 3 HP capacity
	Precision two-stage design
	15 micron vacuum level
	1/4", 3/8" flare and 1/2" Acme ports
	Built-in vacuum gauge
	16 oz oil reservoir
	20 lbs weight
	9.2"h x 5.1"w x 10.5"l
	50/60 hz,115v 1/6HP motor
	16 oz (1 fill) pump oil included

079-0250

$314.95

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