W.C. Gas pressure [Archive] - Coinwash The key to a successful Laundromat Business.

Lar Hylobates

11-20-2002, 12:30 AM

I consider myself to be relatively educated when it comes to BTU's and pressure, etc. I was top of my class in physics, you know. Please don't quiz me as I did alot of cheating and really can't remember any theory at all.

I need a lesson on Water Column W. C. ..What do you do when different equipment has different recomendations?
I have contacted the Gas company, and they tell me that the W.C. thing is outdated and the only thing to worry about is my line size and for me to let them worry about the pressure.

Anyone got the goods on this subject?

CharlieS

11-20-2002, 05:18 AM

Oh , yeah, that's good . TRUST US, We're from the government and we're here to help you!!!

Sorry, settling down, now, breathing getting under control.

Generally speaking, gas appliances are standardized, and the local gas company should be controlling your pressures to remain within standards. However, we don't really want any problems, and so that leaves it up to us (or our specialists) to make sure everything is really OK.

The basics of gas are that the greater the pressure, the greater the flow. Even minor variations can have great impact on the efficiency of your machines, and the happiness quotient of your customers.

With natural gas, the gas usually has a primary pressure set at the meter regulator, which must be within the specifications set by the manufacturer. It takes very little time to verify. Then the appliance regulator will bring it to final pressure. These systems are pretty good, and probably don't need a lot of tweaking, but it doesn't hurt. Small variations can create heating differences among your machines.

LP gas has only a single primary regulator, and is fed directly into the system after that. As a result, setting your pressure accurately and having the correct size orifices can make a significant difference in the performance, economy, and efficiency of your machines.

WC inches can be measured using a simple water column gauge which can be purchased at most heating supply wholesalers. It is very accurate, literally weighing water against the pressure. These are low pressures, and most analog gauges don't go that low. You can buy analog gauges from Grainger.

Bottom line. Have a good HVAC tech check over your systems. Make sure he verifies pressures in accordance with manufacturers specs.

anonymous

11-21-2002, 07:55 PM

The "water column gauge" is called a manometer, if memory serves. And they don't cost very much (Grainger) compared to fancier gizmos. Our local gas companies are still using them.

Check the manual for your boiler(s). They should require the most gas pressure. Probably simplest to use the manometer at one of the dryer hook-ups. If you have enough pressure for your boilers, you probably have enough pressure for the dryers, etc., but check your manuals to be on the safe side.

Last January, my distributor told me I had only half the gas pressure needed to run my big, newly installed 75 lb. Wasco dryers, and THAT was why they were not functioning correctly. I asked him how in the heck my boilers were both running fine when they required about 25% more pressure than the dryers, and were way at the back of the store to boot. He whipped out his manometer to prove there was low pressure, but he was only reading one side of the "horseshoe" (both sides must be added together). He was totally embarrassed after I told him how to read the darned thing.

Oh, the problem wasn't the gas pressure, it was too much air. The Wascos have a cute little air vent regulator under the exhaust vent at the back of the dryer. It was open too far, and there was so much air cruising through the dryer that the burners kept blowing out. Had to call the NY on that one, as there was no mention of the regulator adjustment in the manual!

Lar Hylobates

11-21-2002, 11:54 PM

Amazing...so you just unscrew the appliance and plug in the meter.

How easy is that??? I'll do that just for kicks if nothing else.

Thanks,

Rondo

11-22-2002, 01:11 AM

Bubbles sound like she is handy to have around a mat. Good for her, sound like the she's captain of the ship. :D

SudsMan

11-22-2002, 10:53 PM

I hope I'm not falling for one of HLs "unusual" comments... but when I read that all one has to do to use a manometer is to unhook the appliance and hook up the manometer... well, I just had to weigh in.

So here goes nothing. The manometer connects into a test hole in the gas valve. This looks like a recessed allen head screw. The gas must be turned off if you are measuring the upstream pressure. The manometer is connected via a 1/8" male fitting and a flexible hose that terminates at the manometer.

The appliance MUST be operating to get an accurate pressure reading. If it isn't you'll just read the static pressure that means nothing. Natural gas pressures for most dryers and boilers will be in the 3.5 to 5" WC. This isn't a lot of pressure. About equal to a pound and a half gauge. The pressure MUST be set to the manufacturer's specifications or you will run into flow, ignition, poor efficiently problems and such.

So, DO NOT DISCONNECT THE APPLIANCE to measure pressure. That would be a ton of work any way and would only give you a static pressure reading and not an accurate pressure reading under flow conditions.

One more thing. Be sure to check all connections for leaks before you turn the gas back on, even when just attaching the manometer.

The most accurate and cheapest way to go is with a manometer, not a pressure gauge. You'll find the gauge isn't all that much easier to use. You still have to connect it to the allen head plug on the valve. The gauge costs more and are not reliable.

Hope this helps. Hope I didn't type all this for HLs amusement! :-)

Anonymous

11-22-2002, 11:04 PM

Sudsman is 100% correct, static pressure within a piping system means nothing. Take it a step further, if you are building new you should run your gas line as a loop, not a long run that just ends. By having a loop you balance the pressure throught the entire system and it will avoid a lot of problems.

Lar Hylobates

11-23-2002, 02:16 AM

Sudsman,

thanks for the info. I'll actually print this one out which is a rarity.

As I read it, there shoudl be a "test connection" but there is not.

This connection is "a 1/8 NPT plugged tapping installed immediately upstream of the gas supply connection" as I read it in the instruction manual. I guess my installer missed that line!

I asked him about this and he told me that they hook up to the meter outside to check pressure. Whatever.

Thanks, Now it becomes clear how to read this mysterious WC. It is read directly upstream of the appliance as it is running via this test hole and a manometer. Is this correct? Taking this a step further should appliances be tested with the bulk of the rest of them running to ensure correct pressure under full load?

LOL...I just found out my installer ran no ground lines to the dryers either.

I still love him.

Rondo

11-23-2002, 02:29 AM

HL, the test hole should be on the gas valve and it will be after the built in pressure regulator. it's a good idea to have other dryers working. What size trunk line did they run, it should have been 2"? As Kirby said if you have a lot of dryers you should loop the feed pipe. The loop doesn't have to be 2" you can go down to 1"

CharlieS

11-23-2002, 08:22 AM

There are two different pressures to measure. One is the pressure of the gas feed to the appliance. The second is the adjusted pressure feed to the burner. The first is controlled typically by the gas company regulator, and the second by the internal regulator of the appliance. The gas company regulator needs to be low enough to meet the max capability of the appliance regulator, but high enough to feed all of the machines simultaneously.

There should be two taps. One inside the dryer (or other appliance), which is after the internal regulator, and the other is outside the appliance and installed by the plumber, although some appliances may have an extra tap for this purpose.

I consulted with several engineers on the gas feed to my new store. Ultimately, we elected to feed the gas to the rear of the store at 2PSI in a 2" pipe (normal is 1/2 PSI). We then used a second regulator to step it down to 1/2. This allowed using a smaller 2" line for the long distance. Then we switched to a 3" line to feed the dryers. No return loop. I questioned this, but the engineers were adamant that a properly sized feed would not result in a problem. I attached test gauges to both ends of the dryer line. They were correct. I get equivalent and full pressure at the far end, even with all dryers running. these dryers pull about 2.5 million BTUs of gas when all run simultaneously. We fired them all up within seconds of each other for this test. With the secondary regulator, I can tweak the adjustment easily to spec. (OK, I do have to climb on the roof) I run at 9.7 WC inches. My dryers allow a max of 10. The gauge fluctuates about .1 inches as dryers cut on and off.

These gauges were purchased from Grainger.

Charlie

Anonymous

11-23-2002, 09:12 AM

I'm very surprised your gas company / municipality would let you run the gas pressure that high. Generally they want it low from a safety point of view. That is why you want a loop, but if you can get away with high pressure that is fine. The one (and really only one) nice thing about the utilities in my old store is that when they put it in they ran a loop of 4" gas piping. So, even at low pressure I get a perfect flow balance.

CharlieS

11-23-2002, 10:05 AM

The 2.0 PSI feed and regulator are required to be outside the building. We used this approach to keep from running a larger line to the dryer area, saving on installation costs. We use two regulators to control the pressure, which are set at just below 10 WC inches. (One for the dryers, one for the heaters and water heaters) This meets the dryer specs and allows me to always keep full pressure at the nozzles regardless of demand. In reality, the system keeps full pressure on all machines at all times.

Normal residential/commercial pressure is .25 PSI, which is 7 water column inches.

Here is a web site on how to read a manometer.

http://www.k-sea.com/images/manometer6.pdf

I was curious about the references below to adding both sides to get the WC pressure. The gauge I purchased has the inch levels every 1/2 inch, so that you only need to read one side to get a reading. In other words, check the instructions for your gauge. If whole settings are 1" apart, double the reading, if 1/2" apart, the reading is already doubled.

Charlie

CharlieS

11-23-2002, 10:12 AM

One last thing I did. I installed an electrically controlled gas line cutoff valve in the 2" high pressure line feeding the dryers. This valve is automatically closed when powered off and held open when powered. The security system controls this valve. In the event of a fire, it is automatically closed, stopping all gas flow to the dryers, although the pressure would still bleed down. In addition, it closes the valve after hours, reducing the potential for problems when no one is in attendance.

This valve has a manual shunt control valve that can be used to turn on the gas in the event the valve malfunctions.

Total cost was about $600 to add this valve. I'm hoping to get a break on insurance, but don't have that number yet. My fault, I just haven't submitted the paperwork. CLA has told me that they are pretty sure I will get a reduction of some kind.

Charlie

anonymous

11-23-2002, 10:01 PM

Charlie --

Never seen a manometer marked that way.... the only kind that I've seen, both sides need to be added. My pressure is 6.9 WCI. One side says 3.5, the other side says 3.4. Must be added together to arrive at 6.9 and jive with what the gas company says the pressure should be. Guess I'm getting old and out of date. Don't make fun of me or I'll hit you with my cane.

Never had any problems with irregular gas pressure. I have a 4" manifold running the length of the building behind the dryers, and across half the back to the boilers. No loop, but no problems... at least not in the 33 years the laundry has been standing.

Question.....

Assuming that some of you have repackable gas shut-off valves, have any of you had any experience repacking shut-off valves? The valves at my manifold (trunk line) could probably use a repack job. This is something I've never done..... might need to hire someone. Is it difficult or time consuming to repack?

P.S. To Sudsman: Gee, did I say to unhook the appliance? Can't find any mention of that in my post.... I just figured it would be easier to check the pressure behind the dryers than try to do it behind the boilers. Next time I post I will be more specific so the conclusions aren't jumped on so hard. ;)

SudsMan

11-24-2002, 02:46 AM

Hi Bubbles, my comment about not unhooking the appliance was a reaction to HLs post on 11/21.

I have a 3" main and no loop. I have the connections for the loop and may put it in someday. But no problems with uneven pressure without it. My utility gas guys are most helpful and they told me that 3" and up don't need the loop. But below should have it.

No experience with repacking gas valves. But it sounds like something that you might want to hire out. At least that way you can watch the guy do it so you can do it in the future.

Lar Hylobates

11-24-2002, 03:14 AM

You guys are amazing. This is definitely one of the few times that I have been impressed.

I have had two gas company representatives out at separate times...neither felt the need to check any pressures to my machines and both told me this W.C. thing was overated and outdated. No mention of loop by my installer, distributor or otherwise!

For clarification, I should find this 1/8 tap on the gas valve that transitions the 1/2 black pipe to the 1/2 flex line that is 12" long that feed the dryer. This valve should read 7 -10 WC more or less as spec. to my dryers for inlet pressure.

The tricky part is this...You are telling me that inside the dryer on the burner I will find another tap to read the burner W.C> which is of course to be 3.5 W.C. on my Dexters??

Is the gist of it?? And if it does not work out I need to look into loops and bigger pipe, etc.>>

Rondo, I have a 4" main that branches to 4 - 2" black pipe. Each 2 " pipe feeds 6 stack Dexters or 7 slimlines, depending which bank we are discussing, for a total of 38 pockets, 26 units, or 4 banks.

Can anyone confirm my statements here?

Hell, I am really looking forward to going down there next week. A rare occaision.

SudsMan

11-24-2002, 11:27 AM

Hi HL... a couple of comments.

As for the water column being outdated. What can I say. A WC manometer is the standard by which all other methods of measuring pressure are compared. It is true the newer gauges are easier to use. But they can give you false readings, especially if you are looking for minor variations in pressure. They're "OK" for seeing if there is any gas pressure present. But not all that reliable for diagnosing a potential problem.

Suggest you start at each appliance by looking inside the cabinet. Start at the actual burner and work backwards towards the main gas trunk line. Most dryers will have a gas pressure regulator that is very close to the burner. If there is one there, that regulator should have the 1/8" hex head recessed test port. The port should be on the burner side of the regulator. Some regulators, but not many, have a port at the inlet of the regulator so you can measure the gas pressure that the regulator sees from the trunk line.

If there isn't a regulator inside the appliance, then there should be one outside and still close to the appliance. That regulator will have the same ports as described above.

Going further back towards the trunk, you should be in great shape with a 2" line feeding only 6 or 7 appliances. And the 4" main is surely large enough. Having said all that, the correct approach for determining the size pipe you need is to add up all of the BTUs of each appliance, assuming they are all operating at the same time. Do this for each section of pipe you have. Once you know that number you can find out the size pipe you need. I suggest you ask your utility for their recommendations on pipe size vs BTU load. If they won't help you can get the information from a plumbing technical book, possibly available at your library or plumbing supply house.

You shouldn't need a loop on the 4" pipe. And if the length of 2" is short, like 10' or so, you shouldn't need a loop there either. But if you want to be pure about all this, you could install a loop on the 2" if there is any doubt of the total BTUs and the length of pipe.

Finally, I must apologize for mixing the terms valve and regulator. A valve is an on or off device. A regulator adjusts/reduces the pressure from a high value to a lower value and keeps it there. The ports I mentioned above are located on a regulator, not on the valve. If you have a valve that is used to close off the flow of gas, it won't have a port. Usually. I have seen shut off valves that have a test port built into them on the down stream side of the flow. But these are usually found only in industrial settings where pressures are measured frequently.

Hope all this epistle helps.

Lar Hylobates

11-24-2002, 10:44 PM

Thanks,

helps quite a bit.

I am comfortable with the burner manifold test port, but I want to test the inlet W.C.

My installation manual says to install the test port just upstrema of the dryer connection of course. My installer did not do this even after I asked him about it and the on/off valves that I have definitely do not have a test port. Obviously, I will have all of the dryer inlets upgraded to include this test port.

My question now...is it feasible to look for valves that have this feature or what. What is the most common method of including this test port on the gas line connecting the dryer to test inlet pressure?

I also don't have these test ports on the old dryer inlets as far as I can tell.

Tell me what to buy so I can get these and install them

I have a 2" black pipe w/ 6 1/2 " black pipe stems. Each stem is about 12" long with an on/off valve that feed a 1/2" flex line to the dryer. I want to unscrew the on/off valve on the end of the black pipe and install this test port and again the on/off valve.

Thanks

CharlieS

11-25-2002, 12:40 AM

Hylobates -

You don't really need to have a test port at each dryer. Put a single port on the dryer farthest from your feed, and if you want, a second at the dryer closest to the feed. Test at each end, all the rest will be somewhere in the middle. If your system is set up correctly, the pressure will be the same at both ends, with all dryers operating and firing simultaneously.

Go to Lowes or Home depot. Get a 1/2 T fitting with a plug. If you have room, just unscrew the existing flex line, screw on the T-fitting, and reattach the flex. If this becomes too long, take off the 12" pipe, and add a 6" - 8" piece instead. Of course, use pipe thread dope to seal the threads. Make sure it is suitable for use on gas lines, not all dope is the same. Not too much, just fill all the threads and wipe off the excess, then screw it together. Test for leaks with soapy water. Leak test kits, which are basically soapy water with an applicator, are available at most Lowes or Home Depot.

Once you have your manometer, buy a reducer fitting that matches the thread size on the gauge. You may have to stop at a plumbing supply house to get that. You can buy the gauge there too, as well as the T- fitting and the pipe dope. OK, skip Lowes or Home Depot. The counter guys at the plumbing shop will be able to give you what you need, as long as they know the size pipe you have.

Hopefully, it goes without saying, cut off your gas first!!!! Have your pipes ready to go and keep the area well ventilated with no sources of ignition. Do this before or after hours, when the other dryers are not running. Get the new pieces started quickly. No Smoking. Safety , Safety , Safety.

Or hire a plumber. If you have a regular plumber, this a quick and simple job.

Charlie

Lar Hylobates

11-25-2002, 01:14 AM

Thanks,

that's what I needed to know. I will have my installer come back and do this as I don't like getting blow up or electrocuted. I just want to make sure he gets it right this time so I need to know everything about what we will be doing.

Can't wait to get my manometer!!

SudsMan

11-25-2002, 01:50 AM

One more thing to be aware of. If you have to shut off the main gas valve in order to do the upgrades Charlie S. described, you will be taking the complete load off of the utility's gas regulator that is outside of your building. No problem shutting it off.

But, when you turn the main back on, you MUST do it VERY slowly. This is so that the utilitiy's regulator doesn't see a huge load coming on over a short period of time and hence thinks there is a leak. If the utility's regulator thinks there is a leak it will shut down all by itself. This is a safety feature built into the large regulator. And guess who you have to call to reset the regulator's safety cutoff??? Yup, your friendly utility.

You may want to confirm that your installer knows of this situation. He/she should.

BTW, when you put in the T that Charlie S. mentioned, you should also put in a ball valve shut off at the bull of the T. This way you can connect the manometer without having to shut off the gas upstream. Just open the ball valve after the manometer is connected.

And just to say it one more time, and quoting Charlie S...... safety... safety... safety...

Lar Hylobates

11-25-2002, 01:03 PM

thanks again...

my gas has been on and off several times and I have watched them do it not so slow. So far no problems, but thatnks for the info.

I had definitely intended the individual valves to be upstream of the test port for that reason.

Incidentally, each of my 4 - 2" feeds has a brass "ball valve" installed for the purpose of shutting down the bank of dryers without shutting down the store. I had a contractor in there for other reasons last week and when he saw them he implied that they were innapropriate or that the gas company did not like that.

As I think about it, I wonder if they are not "gas" valves, but water valves. My installer claimed that he spent $50.00 or so each and that they were top line Italian valves. They are brass in appearance with the handle that rotates 90 degrees, parallel for on and perpedicular for off. Any ideas?

The city has seen the work and did not say anything, but they also missed the NO GROUND WIRe thing, so I would rather get this right now to avoid future trouble regardless of the city.

anonymous

11-25-2002, 04:58 PM

The latest dryers installed in my store, Wasco 75#ers, came from the manufacturer with this type of valve. They have the lever that rotates 90 degrees -- perpendicular to the line when off, and parallel to the line when on. They have YELLOW handles to denote they are for gas usage. The ones I have for water usage have GREEN handles.

I didn't need to use all of the dryer valves as most of my existing valves were in good shape.... my distributor walked off with the surplus. I made him ship them back to me. Got to watch the distributors like a hawk -- they giveth, but they also taketh away!

I only use my distributor when I have something incredibly messy or heavy to do. I make them earn that $75.00 an hour!

P.S. When putting in gas valves or running new lines to the dryers or boilers, don't forget to use the YELLOW gas thread tape. My distributor used WHITE tape normally used in water plumbing, and I made him take everything apart and start over with real gas tape. Totally surprised when he told me that they always use the white tape on dryer and boiler installations! Not in my store, Bucko.

SudsMan

11-25-2002, 06:46 PM

Bubbles brings up some more good points. As for the type of thread dope to use, one brand name of the yellow variety is Rectoseal. Folks in the trade have a rather affectionate nick name for it. Can you guess what it is???

Also, one should never use any type of tape on gas pipe threads. The tape will deteriorate after a few years and you will get pin hole leaks. If there is a special tape that's made for gas, make sure it is compatable with the gas you are using (natural or LP). If someone knows the brand name of such a tape, please let me know. I'm not famliar with such a tape but am very willing to learn about it. As a side bar, it's a good practice to use both the white teflon tape and the Rectoseal when threading water pipe.

The valves used on gas MUST be labeled for gas use and be UL listed for same. The color of the handles doesn't make any difference. For example, Apollo makes ball valves that have yellow handles and are rated for WOG (water, oil, gas). BUT, the gas this valve is rated for is a non-fuel gas, such as air. For a valve to be rated for use on a fuel gas, it must be UL listed as such. BTW, green also doesn't mean water nor does blue. The color has to do more with the manufacturer. It's true that the color yellow is used for marking gas lines and for showing gas pipe locations underground. But that's about it.

HL, it could be that the contractor that told you your 2" ball valves weren't appropriate might have meant that they weren't for use on a fuel gas.

Hope this helps.

anonymous

11-25-2002, 07:32 PM

I learn so many new things on this board!

Here I was always told that all the stuff related to natural gas, ie. pipe from the main to the building, thread tape, valve designations, etc. were always yellow. Even the marking tape used on my manifold is yellow with the words "GAS" printed at intervals. How confusing for everyone when trying to find fittings and supplies at the store.

My gas valves with the yellow handles are UL listed for N-gas.

Will check the brand of tape we have used in the past.... some of these fittings were taped 33 years ago and there are no leaks at the threads. I go through these about every six months with a gas sniffer and have found no leaks yet. Fingers crossed.

Thanks for the tip on Rectoseal. I have a feeling I may need it in the future.

CharlieS

11-26-2002, 12:51 AM

A gas sniffer. Now I like that idea.

Lar Hylobates

11-26-2002, 03:48 AM

Two points.

My dryer burner regulators have what appears to be this test port on both sides, before and after regulation to the burner which solves my port problem if I ever had one.

Do these test ports measure about 3/8" in diameter with a 1/8" hex allen key style center?

Secondly, I took the tag from one of my 2" ball valves. It reads as follows...is this fuel gas or not?

WATTS Regulator
2" FBV-3 Brass Ball Valve
Full Port - Thread - 600 WOG
UL listed 7R60

SudsMan

11-26-2002, 09:09 AM

Yes, the ports will appear to be about 3/8" diameter with a allen head. The actual plumbing size of tapped hole that the plug is filling is an 1/8". Be sure you use dope on the threads of any adapter you use to attach a manometer. Also, use dope when you replace the plug. BTW, I've found that the plugs have a great desire to escape from laundromats! They just seem to want to drop to the floor and roll around under things, never to be heard from again....

The brass valve that is labled WOG is NOT approved for use on fuel gases. WOG stands for Water, Oil and Gas. But the gas has to be a non-fuel gas such as air, nitrogen, argon, etc. There must be a tag that has the UL label on it for fuel gas. Nibco is about the best brand you can get for a reasonable price. Fuel gas ball valves is not a place to scrimp to save a few bucks. My local utility has some great people working for it. Most have good senses of humor. One remarked what the effect of an explosion from a 3" main might be... a big hole. As in the gound.

A gas sniffer is a great investment. Mine cost me about $175, if I remember correctly. I went to my utility to ask for advice on this.

Lar Hylobates

11-27-2002, 02:33 AM

sweet.

I'll have it fixed.

Thanks.

David

11-27-2002, 10:07 AM

SudsMan saidIf there is a special tape that's made for gas, make sure it is compatable with the gas you are using (natural or LP). If someone knows the brand name of such a tape, please let me know. I'm not famliar with such a tape but am very willing to learn about it.

I bought my roll from Lowes. On the label - Oatly, Cleveland OH #31403A Full density - Yellow Gasline PTFE tape.

And on the back label - For use on thread joints of metal pipe (not exceeding 1 1/2 in. pipe size) in assemblies handling gasoline, petroleum oil, natural gas (pressure not over 100psi), butane, and propane.