Vacuum Pump CFM

[w.l.ong]

Hello,
i like to know how to calculate a vacuum pump capacity cfm, use for vacuum big chiller like 1000 Ton,

Thanks,

[verstep]

Hi! Based on my experienced dealing with AC Chiller Units and higher tonnages. I don't have calculation as long as within the range of safe where no moisture present. You need to isolate the unit each part by part. Use the dual stage vacuum pump. Add refrigerant then purging.

[The Viking]

First of all;
PLEASE DO NOT PURGE SYSTEMS WITH REFRIGERANT, the polar bears are already suffering and dying.
Use nitrogen instead.

When it comes to vacuum pumps;
The CFM itself is less important, a small pump correctly attached to the system will pull a quicker vacuum than a larger pump connected through a manifold.

Instead of using manifold and hoses, use CU-pipes and flares, also, utilise "valved" service ports and not schraeders (if you have to, use a core removal tool). This will speed up your work more than a larger pump will do.

Good luck.

[sedgy]

why not try the tripple evacuation method , using a torr gauge when at desered vac add ofn up to atmosferic pressure then do it twice more.

[Peter_1]

Sedy, i use the same technique but only twice.

[Grizzly]

Hello,
i like to know how to calculate a vacuum pump capacity cfm, use for vacuum big chiller like 1000 Ton,

Thanks,
This post is slightly old now.
But just in case it's still relevant,
Yellow jacket reccomend that when a system is 60ton and above,
11CFM is required. (and a lot of patience!)
Grizzly

[sedgy]

so I take it that nowboady has used the tripple vac system ? well it is faster

[Brian_UK]

so I take it that nowboady has used the tripple vac system ? well it is fasterWhy do you take it that way.

Most people know of the triple evac and can/do use when required.

[platinumfreeze]

Can someone explain the procedures of triple vacuuming? Thanx

[Tony]

Triple evacuation

1. Recover system charge.

2. Replace filter drier and pressure test.

3. Evacuate to first stage pressure. (e.g. for 20C - 31mbar)

4. Break the vacuum with OXYGEN FREE dry nitrogen to ¼ barg and hold for 5 min.

5. Evacuate to second stage pressure. (e.g. for 20C - 25mbar)

6. Break the vacuum with OXYGEN FREE dry nitrogen to ¼ barg and hold for 5 min.

7. Evacuate to third stage pressure. (e.g. for 20C - 9 to 11mbar)

The plant should now be sufficiently dehydrated and suitable for recharging.

[Gary]

The volume (CFM) ratings on vacuum pumps are with the intake wide open. Volume drops considerably when the pump is pulling through gauges, hoses and fittings.

Try breathing through a straw and you get the picture. How much air you get depends upon the diameter of the straw.

Similarly, when evacuating, the size of the hoses and fittings is more important than the volume rating of the pump.

[US Iceman]

It also helps if you pull from multiple locations in the system. Pulling a vacuum from a single point is similar to using hoses with high flow restrictions.

I like the concept of using copper tubing also, instead of charging hoses.