Flowmeter settings

[cope]

What pressure are flowmeters set at? I read one place that they are pre-set at 50 psi and another place said 20 psi. I am referring to pressure from the tank, not the flow to the mig gun. I run C-25. TIA

[morpheus]

I think mine came set at 25 right out of the box.

- jack

[Guest]

In my experience, 20 CFH is too low...40 to 45 is about right.

[Bob]

Cope,

I think you understand this already, but just to be sure: The regulator and guage are actually setting (regulating) and responding to PRESSURE.

The dial is labeled with the FLOW (CFH) that will result with a specific orifice size from that pressure. (The right orifice is usually built into a regulator/gauge set.) Some gauges may be calibrated for larger or smaller orifice sizes.

The constant for any given flow gauge is the orifice size. As you adjust the knob/screw, you increase the pressure and thus the flow that will result with the fixed opening. More pressure, more gas gets pushed thru the little hole.

You should adjust for a desired flow with a "valve open" or "purge" condition.

Hope this helps ... seemed like PSI and CFH were getting mixed in earlier responses ... but this could be my "senior moment" understanding.

Bob

[Guest]

Originally posted by Bob
Cope,

I think you understand this already, but just to be sure: The regulator and guage are actually setting (regulating) and responding to PRESSURE.

The dial is labeled with the FLOW (CFH) that will result with a specific orifice size from that pressure. (The right orifice is usually built into a regulator/gauge set.) Some gauges may be calibrated for larger or smaller orifice sizes.

The constant for any given flow gauge is the orifice size. As you adjust the knob/screw, you increase the pressure and thus the flow that will result with the fixed opening. More pressure, more gas gets pushed thru the little hole.

You should adjust for a desired flow with a "valve open" or "purge" condition.

Hope this helps ... seemed like PSI and CFH were getting mixed in earlier responses ... but this could be my "senior moment" understanding.

Bob

I missed that, Bob...DUUHHH! You are so right! It is I with the senior moment! (again!)

[cope]

flow

Bob, I talked to my friendly welding supplies guy and he basically told me the same thing; open the flowmeter valve fully and adjust the regulator for full flow on the meter. He said any more was a waste. Don't know what psi this relates to and as stated, due to varying orfice sizes, I guess it doesn't matter now. Appreciate the replies

[Roger]

If you look at manufactures catalogs on line you will see that each uses different orifice sizes....some manufactures even use different orifice sizes for different purposes.

You asked about flowmeters which around welding are ball in tube flow indicating devices. Supply to them is about 30 to 50 psi depending on brand.

The flow indicating device that looks like a round pressure gage with C bourdon tube thats callibrated in units of flow for given orifice size is called a flowgage.

[cope]

flowmeter

Roger, I have a flowmeter, but it also has provision for adjustment as a flow gauge or regular regulator has. Only difference is that it has a recessed allen head instead of the typical tee handle.

[Roger]

Example flowmeter with regulator.

http://www.smithequipment.com/products/regul/singleflow.htm

http://www.smithequipment.com/products/regul/econflow.htm

http://www.smithequipment.com/products/regul/h1970580.htm

This example isn't practical for most, or elegant. Single balanced piston regulator would be elegant.

http://www.smithequipment.com/products/regul/twostageflow.htm

Example flowgage with regulator.

http://www.smithequipment.com/products/regul/singleflowgauge.htm

Most regulators for flowmeters are diaphram type preset at factory at required pressure but user adjustable with screwdriver or wrench. To adust the regulator outlet pressure you must install LP gage and know set pressure. Manufacture or dealer can supply required set pressure. Insalled LP gage is also usefull to observe excessive pressure creep which can predict regulator failure. Seldom ever done by weldors.

Piston regulators as used in for Smith's
Economy H2051 Series Flowmeter Regulator often are not adjustable except by spring shims during assembly. The piston has 2 O-rings and 1 crimped in soft seat. One spring is used. Very simple and reliable regulator with no patent.

[cope]

flow meter/flow gauge

This is my Pow Con 160 amp MIG/200 amp Stick machine wih the Airco regulator in question.

[Roger]

Nice little welder.

If that is a relief valve protruding down at 45 degree angle on bottle side of regulator what pressure is stamped on it? With no gage to indicate excess outlet pressure creep the relief valve will indicate regulator problems by letting gas escape. If regulator doesn't have unused LP port that can take a gage install brass pipe tee between regulator and flowmeter so you can install 150 psi gage. Then you can see what your regulator is set at. Remove outlet hose from flowmeter then slowly open bottle valve watching that LP gage doesn't see excess pressure. Then open and close needle valve to see what happens to regulated pressure. I am more use to doing this with a scuba regulator and using a small globe valve but the regulated pressure should change less than 5 psi more like 1 or 2 psi with no slow creep up higher. If the regulator pressure almost stops climbing when valve is closed then slowly creeps higher another 5 to 10 psi, The pressure it stops at before creeping higher is about the set point. This is easy to see when using a globe valve but might be hard to see with needle valve. A good regulator will creep less than 2 psi if it creeps 5 psi it is usable but needs overhaul soon. More creep or just high rate of freeflow it needs overhaul. When you look into a disassembled regulator body at the orifice which looks like a small cone shaped volcano with hole you will see small gooves eroded by gas flow. Normally new soft seat and springs will solve problems but eventually the grooves get too deep and new expensive body is needed or repairman could lap top of cone.


The real use for knowing your regulator set pressure is you can then buy another flowmeter for that pressure and tee it in next to original so it can be used for back purging.

Bare in mind this is from lots of experence repairing lots of regulators of various kinds 10 years ago but not that exact model.

Relief valves on regulators are normally set to protect outlet pressure gage so if relief valve is set at 40 psi the regulator might be set at 30 psi max.

[cope]

relief valve

Roger, it is a relief valve, but unmarked. As I posted earlier, I followed my supplier's advice ( opened the tank valve, opened the flowmeter valve fully and adjusted the regulator for full flow on the meter. I will pull the flow meter off the regulator body and hook up a gauge to see what pressure this gives me.

[Roger]

Your flowmeter looks like a victor. Here is link to index that links to their products including flowmeters. I can't download that PDF file now without getting error message.

http://thermadyne.com/vec/literature/index.asp?div=vec

Here is flowmeter for checking flow rate at torch end.

http://weldingdirect.com/gasflowchecker.html

[cope]

flow meter

Actually it is an Airco.