Measuring a specific air pressure

It is called a pressure gauge.

There must be more to the question.

measure water column height,10 m equals one bar, and quite accurate.(but a little bit clumsy). Or use mercury, 1 m 52cm for 2 bar.

Well...you could use a pressure switch - closed above 30 PSI, open below

30 PSI - could be quite accurate but gives you very little precision.

What, exactly, are you trying to do? How accurate? How precise? How much money do you have? How many times a second do you need to update the reading? Analog or digital?

Are cryogenic fluids involved, or hot combustion gasses, or corrosion, or ionizing radiation? Does the measurement equipment have to be food-safe, explosion-proof, FAA certified, FCC type-accepted, CSA/UL registered, IEC standard or ISO 9001 registered? Must it have a GSA number? Will you be using this on a submarine or a space vehicle? Can it use proprietary intellectual property or must it be open-source and public domain?

Must the measurement be made available remotely via a Web server or is a pointer on a scale good enough? What units of measurement do you need? Does it have to be traceable to NBS or other national standards laboratory? Will it be used by carnies, cops, convicts,con-men, consumers, Christians, cowboys,coxswains, copywriters, co-pilots or others? Are you allowed to use mercury, cadmium, nickel, asbestos, PCBs, or volatile organic chemicals?

Must it be movable by a batallion, air-dropped, man-portable, pocket-sized, implantable,or permanently installed? Should it float or be waterproof or be submersible? What temperature range is required? Indoor or outdoor? Does it need an RS-232 interface? Bluetooth? Zigbee? International Morse Code at 25 words per minute? Must it be painted in your corporate colors?

Is it a one-off or will you be ordering a million units per year? What field service organization is required to support it? Can it be maintained by a team of graduate students or must it be field-repairable by a Third World bicycle shop? Must it be legal to export to North Korea? Will it be used in a life-support application? Must it be made of biocompatible materials? Should it be recyclable and comply with ROHS directives? Does it have to have a warranty? A guarantee? A patent? A license? What happens if the measurement is no good?

some of these questions may be relevant; answers to many of them would allow others a better chance to help you.

Bill

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I'm trying to verify a couple of tire pressure gauges.

They are notoriously inaccurate.

All I need is a reference point accurate to plus/minus 1 psi.

Thanks for the reply.

Jack

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Thanks for the response.

I'm trying to verify a couple of tire pressure gauges.

They are notoriously inaccurate.

All I need is a reference point accurate to plus/minus 1 psi.

I think that I have a slight learning curve to convert "bar" to "psi".

Jack

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Sorry, I wasn't specific on my requirements.

Please read my response to other posters.

Jack

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1 PSI is 1/30th of 30 PSI, which means you're looking for a pressure
gauge with an accuracy of +/- 3.3% or better.

Try this:

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GFRC,GFRC:2006-50,GFRC:en&q=pressure+gauge

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Thanks very much. I'll check those out.

Jack