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Does anyone know what this is please?

Brass 'Sarco' tool

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Jon Craig-Tyler07/10/2018 11:41:42
3 forum posts
2 photos

Not sure if I'm posting this in the right place, but here goes.

I came across this bit of equipment in my granddads garage and I'm trying to find out what it is.

It is made of brass, stamped 'Sarco' and contains some sort of measure? I'm thinking it's something to do with a pressure gauge, but could be way off the mark.

Would be grateful for any help in identifying.

Thanks in advance.

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Nick Clarke 307/10/2018 16:18:14
72 forum posts
1 photos

Only guessing but perhaps a manometer to help balance carbs on a car or bike??

mick07/10/2018 16:35:18
350 forum posts
25 photos

'U' gauge for testing gas pressure

The Oily Rag07/10/2018 16:44:31
48 forum posts

I think Nick is on the right track, It looks very much like a small manometer. The Spirax Sarco company still exists and is very much involved with pressure measurement instruments. I cannot find this exact item however.

regards

Ian

Martin Connelly07/10/2018 17:56:10
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704 forum posts
71 photos

Are the markings 1/2" apart? If so it is for measuring 0-3" water gauge pressure or vacuum. There should be some coloured water in the tube and when both ends of the tube are open to atmosphere the water columns should line up with the 0 on the scale. The presure is read as the difference in height between the two columns. Low pressures like this are still measured with modern gauges that give readings in inches of water. Typical uses would be for measuring air pressure in a venturi or either side of a filter where a high reading would show the filter is clogging up or flow through it is high. If filled with mercury it would work for higher pressures but is more likely that water was used.

Martin C

Jon Craig-Tyler08/10/2018 11:32:00
3 forum posts
2 photos

Thanks for all the info.

I've tried Spirax Sarco customer services, who were very polite but didn't have any info, unfortunately.

There's no unit of measurement on the scale and each whole number is sub-divided into 5. There's no liquid present, but would suspect that it would hold water, as doesn't seem to be any mercury residue.

So is it fair to say the consensus is a pressure gauge?

Again, thanks for all your help.

Jon

Ian S C08/10/2018 11:37:24
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7017 forum posts
224 photos

A manometre of a similar range is(I think) used for checking the draught of a chimney, you want it to be positive rather than negative.

Ian S C

Martin Kyte08/10/2018 12:50:31
1318 forum posts
9 photos

Well it's definitely a pressure gauge. Judging by the presence of two fittings it would suggest the measurement to be differential in nature. If the markings are 1/2 inch apart the the readings will be in inches (probably of water) 1inch would correspond to 0.036 psi. The metal transit case would lead one to think that it was for field use rather than lab or workshop. The pressures involved as Ian has suggested (chimneys) would fit with setting up draughting arrangements so ventilation usage may fit. Coal mines come to my mind but as far as I know they used portable anemometers as the were more interested in flow rates than pressure differences but someone may know better. However due to the very low pressures indicated would lead me to think that either the device was intended to measure balanced pressures. However if it was used in conjunction with a pitot tube already installed in a pipe it could well be used to measure flow rates.

That is about the limit of my deductions.

regards Martin

Neil Wyatt08/10/2018 14:40:37
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14424 forum posts
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It's not for mercury, mercury wets brass.

Michael Gilligan08/10/2018 21:18:33
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11757 forum posts
518 photos

The generic illustration of a u-tube manometer, here: **LINK**

http://electricalninstrumentcad.blogspot.com/2015/

looks remarkably like the Sarco device.

MichaelG.

Ian S C09/10/2018 12:40:52
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7017 forum posts
224 photos

Some where in my memory bank is pressure testing the air cooling systems of high power radio and radar transmitter output valves such as the VT 98, I'm not sure how this was done, my information source(Dad) is nearly 40 years gone.

Another thought, drains require to be tested to 1" Hg or 5 psi (I don't know if those are the same, got info from different places).

Ian S C

Edited By Ian S C on 09/10/2018 13:03:02

SillyOldDuffer09/10/2018 13:07:35
3311 forum posts
658 photos
Posted by Ian S C on 09/10/2018 12:40:52:

Some where in my memory bank is pressure testing the air cooling systems of high power radio and radar transmitter output valves such as the VT 98, I'm not sure how this was done, my information source(Dad) is nearly 40 years gone.

Ian S C

That's right.  It's easier to measure air-pressure than air-flow in these systems, so air flow was inferred from the pressure drop between the input and output.

To measure air-flow through the valve, the effective output is inside the cabinet, not atmospheric. The pressure difference equivalent to the required flow would be established by the designer, and maintenance guys would periodically check that the cooling system was operating at that pressure without having to power down the transmitter. Partial blockage of the input filters, or fluff building up in the outlet or the valve's base or cooling fins all show up as off-specification pressures that would require a power-off clean-up.

A manometer is a cheap and way of occasionally measuring pressure differentials; the alternative is to fit a pair of permanent Bourden gauges.

I think Nick got it early on when he suggested Jon's Sarco manometer might be for balancing carbs.

Dave

 

 

Edited By SillyOldDuffer on 09/10/2018 13:08:52

Speedy Builder509/10/2018 15:52:40
1570 forum posts
105 photos

Not to hijack the thread, but at BAC Weybridge, we used 'precision' manometers which were inclined at about 60 degrees off vertical which I believe would have magnified the indicated pressure by x 2. ie: 1" of pressure was 2" on the scale. We were measuring pressure points along aerofoil sections. The model had probably 50 or more tiny tubes (0.5mm I/d) drilled into the model and each connected to a bank of 10 manometers. When the wind tunnel operator shouted 'MARK' five of us would note the readings on our board of 10. The readings were punched onto 5 hole paper tape and run through the 'Pegasus" computer.......... Oh, happy days as an apprentice.
BobH

Geoff G09/10/2018 16:11:26
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16 forum posts
2 photos

I think that Nick Clarke, at the top of this topic, has it right. With its very limited range and the connections to either side of the manometer, it is clearly intended to measure the pressure difference between two streams of gas (carb intakes, or whatever. The actual pressure in the system is not relevant, only the variation between the two. The use of water in the u-tube will, of course, give a much more accurate reading (12 times better?) than mercury would, never mind the problems which Neil envisages with the mercury / brass combination.

Geoff G

Meunier09/10/2018 16:45:42
154 forum posts
Posted by SillyOldDuffer on 09/10/2018 13:07:35:
Posted by Ian S C on 09/10/2018 12:40:52:

Some where in my memory bank is pressure testing the air cooling systems of high power radio and radar transmitter output valves such as the VT 98, I'm not sure how this was done, my information source(Dad) is nearly 40 years gone.

Ian S C

/..., and maintenance guys would periodically check that the cooling system was operating at that pressure without having to power down the transmitter. Partial blockage of the input filters, or fluff building up in the outlet or the valve's base or cooling fins all show up as off-specification pressures that would require a power-off clean-up..../.

Dave

Edited By SillyOldDuffer on 09/10/2018 13:08:52

Following a truncated sailing holiday in the mid-60s, my skipper, who had worked at Dollis Hill, called up an old chum who had transferred to the Goonhilly satellite installation and arranged a site visit. We went inside the base of the sat dish and had a guided tour. He showed us a Klystron, from memory about 2'6" to 3' tall on the end of a wave-tube down from the dish and explained that they had to strip the Klystron down to its component parts every month during routine maintenance and thoroughly clean it due to the build-up of fine china-clay dust particles accumulated and passed down by the dish acting as a wind concentrator. From memory (during the Early-bird / Telstar times) the Klystron definitely trumped the recent vacuum-tubes shown by S.O.D and MichaelG.
DaveD

SillyOldDuffer09/10/2018 18:24:01
3311 forum posts
658 photos

If I had a sailing holiday with someone from Dollis Hill that ended Klystron spotting at Goonhilly, I'd assume I'd died and gone to heaven!

bricky09/10/2018 19:15:25
315 forum posts
41 photos

In the building trade we used something like this to test new drains.A solid drain plug at one end and a plug with a nipple at the other ,attach a rubber tube to the plug and the gauge and a mouthpiece tube to the other nipple and blow and watch the gauge for any fall indicating a leak.

Frank

Meunier09/10/2018 20:18:11
154 forum posts
Posted by SillyOldDuffer on 09/10/2018 18:24:01:

If I had a sailing holiday with someone from Dollis Hill that ended Klystron spotting at Goonhilly, I'd assume I'd died and gone to heaven!

It was certainly better than tacking across Torquay harbour for 45mins, taking a look at the waves outside the breakwater entrance, saying 'no way jose' and returning to the beach in 5mins (don't let on to Sam Longley). The weather was so bad it made for an atmospheric trip across part of Dartmoor, prison, mist and ponies, cue Sherlock Holmes. So the Goonhilly visit, including the control-room, was the highlight of our 'sailing holiday'
DaveD

Meunier09/10/2018 20:21:14
154 forum posts
Posted by SillyOldDuffer on 09/10/2018 18:24:01:

If I had a sailing holiday with someone from Dollis Hill that ended Klystron spotting at Goonhilly, I'd assume I'd died and gone to heaven!

It was certainly better than tacking across Torquay harbour for 45mins, taking a look at the waves outside the breakwater entrance, saying 'no way jose' and returning to the beach in 5mins (don't let on to Sam Longley). The weather was so bad it made for an atmospheric trip across part of Dartmoor, prison, mist and ponies, cue Sherlock Holmes. So the Goonhilly visit, including the control-room, was the highlight of our 'sailing holiday'
DaveD

Jon Craig-Tyler10/10/2018 22:18:11
3 forum posts
2 photos

Thanks all for your help with this. Really interesting.

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