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Looking for a reasonably priced flowmeter for gas measurement

Looking for a reasonably priced flowmeter for gas measurement

Looking for a reasonably priced flowmeter for gas measurement

(OP)
We are measuring using a thermal mass flow meter right now and it works great, but I am looking for something under $5K. The application is 20,000 SFPM in a 3" sched 40 pipe

RE: Looking for a reasonably priced flowmeter for gas measurement

How much pressure drop can you take, what turndown do you require, and how much accuracy do you require?

Orifice meters are cheap, but have some drawbacks.

RE: Looking for a reasonably priced flowmeter for gas measurement

(OP)
5 PSI pressure drop, 100:1 turndown and just need repeatability with +/- 3%

RE: Looking for a reasonably priced flowmeter for gas measurement

At 100:1 turndown, you may be limited to an ultrasonic meter selection - doubt it will suit your budget though. Pressure drop is negligible.

RE: Looking for a reasonably priced flowmeter for gas measurement

The turndown is going to be a problem - an orifice meter, even with a good dP sensor, isn’t going to cut it.

I’m not actually sure what other gas flow meters have a 100:1 turndown other than coriolis meters.

Vortex meters might be okay - the one I’ve seen states good accuracy down to a Re of 10,000. Does that give you enough turndown?

In any case, you aren’t getting 100:1 turndown on the cheap.

Is this a clean, non-condensing gas?

RE: Looking for a reasonably priced flowmeter for gas measurement

Branch to several meters, each one sized for various turndown flow ranges, but that gets expensive quickly as well. Covering all bases always has its costs.

RE: Looking for a reasonably priced flowmeter for gas measurement

Ian,

I assume this is 20,000 SCFM? Is this your max flow?

So you also want to measure down to 200 SCFM??

What is the pressure / velocity range?

DO you have space for long (10-20D) straight lengths upstream and d/S of your meter location.

If your current meter works great, why are you looking for something else?

What sort of output do you need? - ready calculated SCFM to what metering spec?

All data that a vendor will need to know.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Looking for a reasonably priced flowmeter for gas measurement

(OP)
Hi Little,

20,000 SPM or 1050 SCFM equivalent for our pipe size, I worked out the specs with the company I bought from before that information is listed here- https://www.foxthermal.com/configure/?AppID=25497

What we have works well, but this is a research facility and I'm looking for a more cost effective solution. we have 10 more measuring points so $50K might be a little pricey.


TiCl4,
It is a composition of non-condensing gases. I will look into Vortex, that might be a good alternative.

RE: Looking for a reasonably priced flowmeter for gas measurement

From memory, you wont get more than approx 8:1 turndown with vortex meters, so you'll need at least 2 vortex meters piped up in parallel to get 70:1 or so ( a low range and a high range meter). Plus you'll need an inline densitometer for mol wt correction to give you a corrected standard volumetric flow readout.

RE: Looking for a reasonably priced flowmeter for gas measurement

To elaborate on vortex, at low flow, there aren't enough vortices generated within the 'reporting' or update time period, so vortex meters report zero flow, a self induced low flow cutoff. Rule of thumb is about 10% of max flow is the low flow cut-off, but it depends on the pipe size and flow, but it's a physics thing that all vortex have to deal with.

Beware. Note that the origin point of a typical sizing chart for the design conditions is not (0,0); the flow cuts off in the example at 15.2 GPM, any lower flow rate is reported as zero.

RE: Looking for a reasonably priced flowmeter for gas measurement

(OP)
georgeverghese,

I think you are correct from what I have read up on the vortex meters.

danw2,

Thank you for elaborating on why the vortex meter is probably not suitable. I found a less expensive model of the one we originally purchased from the same company so I think I'm good for my gas flow measurement needs.

RE: Looking for a reasonably priced flowmeter for gas measurement

Quote (Ian godfrey)

I found a less expensive model of the one we originally purchased

Which one?

And does it do 100:1 turndown??

Still don't know what 20,000 SPM is though... "Something Per Minute"??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Looking for a reasonably priced flowmeter for gas measurement

(OP)
Fox Thermal's model FT1, apparently it can go higher than 100:1. I was looking at 20,000 SFPM standard feet per minute in a 3 inch schedule 40 pipe. It can also switch between gases like the FT4A we have.

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