Digital Pressure Gauge

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Graham Sherwood

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I am researching this for a volunteer group who would like better info over the pressure over time aspect of their boiler.
This for a full size steam tug which does river cruises and has to navigate locks etc.
So warning if the boiler pressure is rising or falling over say the last minute would be very useful.
At a first pass I can’t find any commercially produced item, and are wondering if a pressure transducer / analog to digital converter / micro computer like a Raspberry Pi or Arduino would be feasible.
I have used a Pi before and am comfortable with the programming, but not the hardware aspects.
Probably a long shot - anyone on here done something similar?
Thanks
 

johnmcc69

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Maybe check with some companies that specialize in steam generators/pressure vessels. Fulton boiler works comes to mind..

John
 

BaronJ

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Hi Graham,

Grab a cheap digital tyre pressure gauge from Motosave or Halfords. They have all the bits you need.
 

ddmckee54

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I can think of a number of digital pressure transducers that I've used, IFM Effector comes to mind. You didn't mention give any specifics on your electrical system, but I'm pretty sure they're available in AC or DC. We use the Effector's on pneumatic transfer lines, and you can get them in various pressure ranges. I'm not sure if they're steam rated but I think they are.

The problem is that you want not just a pressure transducer, but something that will do a historical trend. There's probably software out there that's does historical trending that is compatible with the Pi. I'm pretty sure that Pi's have been used for data logging which gives you the history but not the trend.

It sounds like you're only interested in the last 5 minutes, so you don't have to worry about keeping an inordinate amount of data points. You don't need the sample rate to be too high either, the boiler pressure isn't going change that much between samples, even it your sample rate is only once every few seconds.

Don
 

Peter Twissell

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As an alternative to an electronic / digital solution, there is a fairly straightforward mechanical option.
Aircraft have a climb / dive indicator, which is a differential pressure gauge with a very small bleed into one of the chambers.
As pressure changes at the point of measurement (in your case, the boiler), it changes more slowly in the side of the gauge which is connected via the small bleed and the gauge shows the difference.
At any time, the gauge shows the rate of change of pressure e.g. PSI/minute.
For a boiler, this could be made from a normal boiler pressure gauge by fitting the gauge inside a pressurised housing, which has the small bleed connection to boiler pressure.
 

swst

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I am researching this for a volunteer group who would like better info over the pressure over time aspect of their boiler.
This for a full size steam tug which does river cruises and has to navigate locks etc.
So warning if the boiler pressure is rising or falling over say the last minute would be very useful.
At a first pass I can’t find any commercially produced item, and are wondering if a pressure transducer / analog to digital converter / micro computer like a Raspberry Pi or Arduino would be feasible.
I have used a Pi before and am comfortable with the programming, but not the hardware aspects.
Probably a long shot - anyone on here done something similar?
Thanks
Please try to SMC
https://www.smc.eu/en-gb/products/sensors-switches~22317~nav
https://www.smc.eu/en-gb/products/pressure-switches~22338~nav

or Burkert
https://www.burkert.com/en/Products-Applications/Your-Fluidic-Challenge/Pressure/Pressure-measurement-and-control
 

vederstein

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Omega.com Find a pressure transducer with a 0-5V output. That can be fed to a basic Arduino for pressure readings.
 

Mike Henry

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Omron sells electronic pressure gauges as well as is a pretty good brand. It might be good to also install a regular pressure gauge as a backup. Digital gauges can do funny things over time, especially if subjected to steam.
 

kiwi2

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Hi Graham,
One thing you might like to play around with is to measure the temperature of the steam before it is throttled. Water at 150psi boils at 181.5C while water at 145 psi boils at 180C. If you used teflon coated k type thermocouple cable you could put it through a compression fitting with the metal ferrule removed. The cable could then be wrapped with multiple layers of teflon thread tape to form a lump of teflon to replace the metal ferrule. Or you could machine a replacement ferrule from solid teflon with a hole providing a snug fit for the cable. Tightening the compression fitting should give a good seal as the teflon is squeezed onto the cable.
Regards,
Alan
 
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