Vacuum Pumping Sizing

The Primary role of a Vacuum Pump is to remove Air and more importantly Moisture from Air-Conditioning systems prior to regassing.

Moisture Boils off when a vacuum is applied to a sealed system and sufficient vacuum is applied. This is essential to prevent a number of issues that will occur if moisture is left in the system.

Vacuum pump sizing relates to the quantity of air that can be removed over a set period of time and is normally measured in LPM Litres Per Minute or an older measurement of CFM Cubic Feet per Minute. This does not relate to the level that the vacuum can be reduced to which is the most important aspect.

Generally speaking the size of a Vacuum pump is related to the size of the system that it is being used on and below is a guide.

System Size Passenger car – 1.2 -1.5CFM or 34-42 LPM Commercial Vehicles/Trucks – 3-4 CFM or 85-114 LPM Buses and Large Commercial – 5-6 CFM or 142 – 170 LPM

All of Alcius Vacuum Pumps with the exception of the 12V A18-5104 are 2 stage Pumps which means that on the correct sized application will reach the level of vacuum required to boil off moisture in a system.

Vacuum Pumps must also have regular maintenance, ArcTick’s Code of practice states.

A.5.4 Vacuum pump oil should be changed either in accordance with the manufacturer’s instructions or at regular intervals.

We would suggest at least every 50 hours of use and the larger the Vacuum Pump the more oil it requires so it also makes sense economically to have the appropriate pump for your workshop.

The A18-5300 Starter Kit has an A18-5101 128LPM 2 stage vacuum pump so is more than capable of servicing the vast majority of vehicles that come into an average workshop.

A18-5101 Vacuum pump


  • Free Air Displacement: 128 Lpm / 4.5 Cfm
  • Ultimate Vacuum: 40 Microns
  • Stages: 2
  • Motor: 1/2 HP
  • Intake Ports: 1/4 Flare & 1/2 Acme
  • Oil Capacity: 300 ml
  • Net Weight: 10.25 kg

Information supplied and reproduced with the kind permission of Autoinfo.

Published October 15, 2019

Get stories about latest tips in your inbox

Related Products

Related Articles

Refrigerant Recovery Using A18-5106 and A18-5107 to Recover Refrigerant
May 12, 2021
Refrigerant Recovery Using A18-5106 and A18-5107 to Recover Refrigerant
A18-5300 Recovery Recharge Station
October 15, 2020
A18-5300 Recovery Recharge Station
Looking after your Refrigerant Recovery Unit
February 28, 2020
Looking after your Refrigerant Recovery Unit
Testing Externally Electrically Controlled Compressors
September 16, 2021
Testing Externally Electrically Controlled Compressors