So here is the little sucker:
|Penberthy GL-1 Jet Pump|
For quite some time, I've had to be satisfied with the calculations I'd done in selecting this particular Jet Pump; however, it's not a technology I've been previously familiar with and have also been at variance from others who have fitted vacuum exhausters to Sentinels before. So my R&D has not been without some risk as to its success.
My first attempt at testing the jet pump was to connect it to an air compressor. However, this produced a poor result which I put down to the narrow bore of the air feed pipe being less than the bore of the jet pump itself. Thus it was never going to be able to feed sufficient air at the required pressure (around 60 psi).
By a stroke of luck, I found a scrap air cylinder at Midsomer Norton Station that had a 1/2" bore outlet and a valve. I considered that if I could pump this up with the compressor, I could then use it to feed the jet pump from its 1/2" bore outlet, at least for a short time anyway.
So here's the test rig in all its sophistication:
|Jet Pump Test Rig|
This time I was much more successful (which led to my excitement that what I'd calculated actually worked!).
|Vacuum gauge showing 21" Hg with about 66 psi air pressure|
(It's easier to read on its side!)
Here it is in video form: (also on YouTube).
Jet Pump Test