Gas Pressure Problem

Cariguy

There are several problems here. You will get a pressure drop through the piping depending on how much CFH you put through. The burner regulator will also have so much pressure drop built in depending on throughput. Gas regulators should be set with the gas flow on. The best way to diagnose the burner regulator is take a pressure measurement in front of burner regulator at maximum flow. If it is a Maxitrol regulator you can go to their web site at www.maxitrol.com and use their sizing program. That will tell you if it is the right one.

Good luck

Big Ed

Gas Pressure Problem

On this hotel Job which runs a dual fuel Iron Fireman burner. It was switched back to gas in the beginning of the month .The problem was a call for noise and smoke.The first problem that was found was too low of incomming gas only 3.5". The burner needed min. of 5" ....The gas co. was called in and their serviceman screwed in the twin 1 1/4" regulators before the meter all the way in to 5" . He said that's all your going to get out of the meter regulators and he left.

We measured after the burner's 2" regulator with the burner shut ,and tried to set it down to the needed 3" but it had no adjustment. When the burner ran up to high fire the pressure would slowly drop below 2" and the boiler would shake the building . Also when we shut off the burner back pressure in the line blow out the water in the U-gauge. Added note; From the 2" meter the gas supply increased to 3" , ran 20' to the boiler then reduced back down to 2".We measured before the burner regulator as well and the pressure dropped to 1.5"-2" also. Seemed like a supply problem ? Called the gas co. back in and they sent the same serviceman back along with one of their tech . We showed him the burner running pressures . First they check to make sure the street valve was fully open.Then they checked the meter by bypassed it . Still the same problem but during the meter test I noticed one of the meter regulators making more noise then the other and just mentioned it to them if it meant anything. It did not to them but they did replace it with a new one anyway . They said the second is just a back up. We had 7" now but still , the pressure would drop all the way down when the burner ran . The tech said the burner must have a bad regulator and it could be full open. He said there was nothing else left .It did seemed to have no adjustment . Does this seem right ? My nagging thought is even if the 2" regulator were wide open the service should still supply more then 1.5" ... Well in the mean time we had problems locating the 2" regulator so we switched it back to oil ......

[Deleted User]

From your

description of the running pressure drop before the burner regulator, the problem sure sounds like the gas folks' equipment. Might want to insist on a supervisor.

Unknown

Problem seems to be

pressure before the gas company regulator. I assume this is high pressure 25 pounds or higher.

The utility needs to put a guage on the inlet side of their regulator (they have special gauges that read in pounds up to 100 pounds) and also on the outlet side along with gauges on each side of the boiler regulator. With the boiler running at full input if everything is sized correctly there should be no pressure drop. Equipment is supposed to be set up that way.

If the utility can not maintain a steady pressure ahead of their regulators then it is their problem.

From the sounds of your post here there is nothing wrong with the rgulator on the boiler.

Has this boiler fired in the past on Natural gas without a problem? If it did then it is setup correctly and as long as nothing was changed it points back to the utility gas pressure.

Big Ed

Reporting Problem Found .......

The regulator was good and thanks for all the help Guys.The problem was the Iron Fireman end cone fell off . It seems without the protection or air control from the end cone the gas nozzles were subjuct to a veturi affect from the air rushing down the blast tube .The gas was being sucked out ! From what I learned this is a normal problem on the Iron Fireman .The four screws which hold it in place loosen over time from the vibration and fall out . Thanks again !

Unknown

Glad you found the problem, but

I am really confused now as to the problems with pressure readings something isn't right here????

Big Ed

Pressure Problem

Once the end cone was reinstalled the pressures were stable and the regulator could now be adjusted . The gas nozzles points (looking down the blast tube) inward to the center of the blastube right after the oil nozzle . First a row of four gas nozzles then a row of (a guess) 10 more . Without the endcone the gas nozzles are in the opening and perpendicular to the rushing air of the burner fan. The rushing air across the gas nozzles created a venturi which sucked in the gas ,dropping the gas supply pressure. Timmie does this sound right or should I loose another nights sleep again ? The burner is running good with a under 50 ppm CO . The supply is 7" and the after regulator pressure running pressure was set to 3.5"....

Don_4

Gas Presure

Hi Tim, Not sure what your expierince has been with gas burners and I can't say I am familliar with that burner. But, from what I have read in these posts, this burner was acting like a negative presure gase train such as might be found on the weil mclain gold boiler and actually sucking in the gas which will give an erroneous reading.

Unknown

If that burner does that

then it is required to have a back pressure/low pressure shut down device on it so it will not fire if the burner head is not in place. They should thank the good Lord it did not fire they would have had one heck of a boom.

No industrial burner should be able to create any kind of negative pressure in the gas line.

Unknown

Ed I think you are okay

I would however look into putting a low pressure gas control on this system just so that does not happen again. A lot of time combination gas/oil systems slip by the underwrriters or it may have been installed before low pressure valves were required.

If you give me a fax number I can fax you some diagrams for piping in both a high pressure and low pressure switch to protect against this happening again.

Big Ed

Great Idea

Sure does make sense to have low-high safety . I will bring it up for a recommendation . I will email you on that fax # .......Thanks again Timmie and Happy Easter