Sufficient vacuum pressure?

[MisterWize]

Swim was wondering if this water pump connected to a glass or stainless steel aspirator will suffice for all lab applications (eg. vac distillation of key products etc etc).
Will a glass one make any difference to the strength of the vacuum?

The pump itself has maximum height of 35m and can pump around 32 litres /min?  can anyone help on this as I have done some basic reading on this but little has helped.

Mw

[homeslice]

How much Horse power is the pump? I think 3/4 hp are recommended.

Swim used to have an aspirator set up for vac distill but since returned his pump and bought a used vac pump that works MUCH better. Swim thinks he spent more money on ice to keep the water in the aspirator bucket cold than he spent on a whole new pump. That whole aspirator setup was inconsistent messy and loud as fuck. Take a look at ritchie yellowjackets which kinda resemble a bee    if swim changed ur mind about aspirators. They're about as much as an aspirator, water pump, pipes, ice and the rest of the set up on our favorite auction site...  

[Rhodium]

Aspirator Vacuum Station

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/aspirator.html)

[Prince_Charles]

Vacuum pumps are much more expensive in Europe. However, you can construct a water-jet pump station in the UK for £ 60 or so.

I compared the specs on several different laboratory water-jet pumps (aspirators): they required between 10 and 15 L/minute at between 1 and 2 bar (10-20 m hydrostatic head). The glass water-jet pumps don't seem to be any better in performance. Bibby-Sterilin polypropylene pumps seem to be as good as any.

You can run (at least) 2 jet pumps from a water pump of that capacity.

You can estimate the pump power required as follows (but this is secondary to the pressure and capacity requirements):

e.g. 10 L/min at 1.5 bar

SI Units (sorry Americans):

10 L/min = 0.167 L/s = 1.67*10E-4 m3/s
1.5 bar = 1.50*10E5 Pa

Power = flow rate * pressure drop = 1.67*10E-4 * 1.50*10E5 W
      = 25 W

Double power to allow for losses in plumbing

Power = 50 W

Assume pump has 50 % efficiency

Pump electrical power = 100 W (1/7 HP!)

Using too big a water pump and running the jet-pump at too high a flow rate won't increase its vacuum any further and will just dump more heat into the water.

I was wondering whether to try running the water pump from a motor controller to reduce the effective power.

[Prince_Charles]

And this is a pdf page from a catalogue with various jet pumps:

http://www.geocities.com/wolfgang_boxhead/apps1027.pdf

I haven't measured the pressure of the set-up yet but it sucks like a tart on Hugh Grant's organ.

I was thinking that if Yankees are using waterbed pumps that perhaps these are not as efficient as a laboratory pump and need more pressure and water flow to get a decent level of vacuum. I haven't managed to find a waterbed pump in the UK but then not as many Britons are sufficiently obese to require 10 hours a day lying in a flotation device.

[BieneMaya]

I bought my high power vac pump from an online auction.

Ok it was sold as defect. But there was just
a little corrusion in the inner pump.
So I got it for about 30 $ incl shipping.

It destills my sassy at about 90 Celsius.

Look out for that old pumps.
Either the engine is defect and can be easily replaced
with some other old e- engine
or there`s just a little corrusion in the pump
that makes the enginepower unable to break through.

But you can clean it and everything`s allright then.
It took me just two hours.

[baalchemist]

Most used high-vac pumps that are apparently 'seized-up' and sold cheaply, are easily repaired. Seizure is usually just a broken vane spring or the little shaft inside the spring is the culprit, also chunky sludge in oil compartment can cause binding. Easily replaceable vane springs & shafts , plus a good internal cleaning will get those old Cenco's & Welch's returned to duty once again.