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Tyre Pressure Gauge


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What do you prefer to use, digital or analogue? My digital one has broken, it reads 10 psi under even with a new battery. Just wondering how accurate they are to start with?

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  • 4 weeks later...

I got a draper analogue one with a bleed valve built in. Its accurate when compared against the local garage air machine which is digital, and its superb when on track days for adjusting pressures quickly. I'd be lost without it given the old girl is a bit picky with her shoes ;)

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I cannot see the accuracy of this anywhere.

Accurracy may not be the problem though, repeatability would be important, provided you had calibrated the gauge to a known accurate gauge.

£10 sounds too cheap!

H

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It's reliable/accurate enough for my needs :) I put air in from the garage or foot pump and adjust when tracking it and thats it. If I know I've got around 32psi in the tyres I am confident enough in the gauge that it will show an accurate drop as I bleed the air out. Its worked ok for me without going too mad chasing absolute accuracy. It's draper generally you can trust that it's good gear IMO :)

 

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The reason I asked about the analogue ones is I've seen them mentioned being used by people who race cars so wondered if I was missing out on anything. Can you calibrate these analogue gauges then?

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The reason I asked about the analogue ones is I've seen them mentioned being used by people who race cars so wondered if I was missing out on anything. Can you calibrate these analogue gauges then?

I'm sure Tony has said in the past that digital is better as there's no moving parts - is that true or have I made that up?

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I'm sure Tony has said in the past that digital is better as there's no moving parts - is that true or have I made that up?

 

It depends upon the sensor arrangements. There are e.g. rare-earth crystals that will generate a small current when pressure is applied to them and they are very stable. You do however need other components - some kind of resistive circuit that will create a high enough voltage to measure - but all the components will have a long life and should be stable for a long time. An electronic device also has the advantage that it can reset itself to zero between readings, so it always starts from the same datum. I am guessing that all of the necessary circuitry is manufactured in some sort of capsule and can be bought off the shelf by gauge manufacturers.

 

Analogue devices that use a moving pointer must use some mechanical motion to create rotation of the shaft carrying the pointer. This might be a bellows of some sort or, quite commonly, a curved thin-walled tube that straightens under pressure. Calibration of a mechanical device is complicated. It needs not only zero and upper max settings, but a matching of the scale to the rate of the tube and consideration of hysteresis. Wear and fatigue affect the stability of the device over time and industrial gauges are re-calibrated regularly.

 

My guess is that the small mass produced devices at the price point we are considering are not individually calibrated, but are subject to sampling checks and depend upon good manufacturing repeatability to achieve reasonable accuracy.

 

Inflation pressures are not an exact science and I think a consistent reading is more important than absolute accuracy.

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In this post Tony made here he said no to digital.

 

Well, if you are comparing a £5 digital gauge with a much more expensive analogue test gauge, that is likely to be true, but if you compare like with like, my experience is that digital wins.

 

I have just looked at the Budenberg catalogue. Their bourdon tube test gauges are generally guaranteed to an accuracy of 0.25% of full range, though they do some special ones with a guaranteed accuracy of 0.15% of full range. Their piezoresistive digital test gauges are guaranteed to 0.1% of full range. The big problem with analogue gauges is that it is actually quite difficult to read them with that sort of accuracy. Analogue test gauges use a mirror behind the scale to help in looking squarely at the indicator, but it's still not easy. Their digital test gauges show all the significant figures and the unambiguous reading needs no judgement.

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Inflation pressures are not an exact science and I think a consistent reading is more important than absolute accuracy.

 

Very true. I've never had any under/overinflated issues using my digital gauge so probably best to stick with it, especially as it's working again now!

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  • 4 years later...

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