High Pressure Hydrants???

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Permalink Reply by Greg Wyant on August 6, 2008 at 10:59am

The hydrants werent hard to open we had hydrants that would flow 2500GPM. We had trouble when I came to the Department with blowing the couplings on our 5in supply line. When I became Chief we went to high pressure hose and had our engines retrofitted with relief valves to handle te pressure. We also went to 2" hand lines and trained alot. Those hydrants have to be opened very slow your hydrant man may have to stand by the hydrant untill you get your water flowing before he can finish opening it all the way.

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Permalink Reply by Chris Steeves on November 29, 2008 at 5:40am

I work on an industrial facility that has 250 psi - 300 psi of static presure at sea level. We have Gleeson Valves for our 2 older engines our 2 new engines can handle the presure. The Gleeson Valves are part of the A.W.S.S system in San Fransisco. I am not sure how we got them but they are great pieces of equipment. They are made of solid brass and are very heavy but hold up well to the salt water that we use. The Gleeson valve provides for control of the flow and pressure into the hose, and absorbs any pressure surge which might occur when a valve connected to a hose-line is suddenly opened or closed.

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Permalink Reply by George H. Potter on December 3, 2008 at 10:52am

Perry,

I just read your comment today, December 3rd. The high pressure Fire water system is quite common in industrial installations. Let's see if any of the following can help you.

- The hydraulic calculations are normally for fixed automatic extinguishing systems; sprinklers, deluge,etc., and more often than not, the designers di not contemplate manual use of the systems. I have experienced several situations in which four brigade members could not SAFELY handle a 13/4 inch handline. Five or even six would be better.
On larger hose, 21/2 or 23/4 inch, at least five; 1 on nozzle, 2 on immediate back-up and the rest just behind these.

- Pressure reduction should probable be at the hydrant, between the connection and the innitial section of hose being fed by that outlet.

- If the apparatus has a pressure relief vaslve it must be adjusted for masx relief. Unfortunately here in Spain,not many pumps are fitted with relief valves as they are generally combined low - high pressure units.

- The hydrant is extremely hard to open at ththis pressure. Adding a 3 - 4 foot pipe to the hydrant wrench and two
well muscled openers may do the trick. Normally the inside stems and valves will take the extra force.

Probably the best advantage for the high pressure hydrant is that high flows are "guanteed".

Keep safe over there.

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Permalink Reply by Irvin Lichtenstein on December 3, 2008 at 12:07pm

In our residential hydrant response zones the average normal operating pressures are 190 PSI at the street. There are two major distribution lines in the eastern end of the township that both run over 2000 GPM at 190 PSI. Our solution, for over 30 years, has been to install dump valves set at 150 PSI on the intakes of all pumps. With the introduction of 5" Storz rated at 200 PSI for supply lines we set all the manual intake reliefs to 175 PSI. We are currently faced with reverting to 3" 600 PSI lines for fire department connections due to height or flow requirements exceeding what the 5" can take.
The greatest operational problem is that pump operators get complacent. Although we carry hard intakes, they are very rarely used and finding a hydrant that cannot sustain at least 1000 GPM at 150 PSI is considered catastrophic. The 2 engines and the quint are all highly automated with electronic monitors and motorized valves.

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Permalink Reply by Pete Yohe on December 3, 2008 at 12:23pm

The hydrants in our area range from 150psi - 250+psi. Basically we do not have many issues with our hydrants; they are easy to open in most cases and have an adequate flow rate. Our engines are set with pressure relief valves on the intake; they are set at 150psi. and thus dump any excess. On the fire scene, once attack line(s) are pulled and the supply lines charged the engine becomes a large gate valve; at transition from tank water to hydrant we reduce throttle (rpm) and gate down on the hoseline to get achieve the proper operating pressure. One other item I would like to mention as to how we have adapted to these high pressures; we utilize gate valves and quater turn valves on all of our engines. This reduces that amount of energy needed to open that valves agains the pressure and reduces our chances for a water hammer.

That couple of concerns we have: During the winter months excess water dumping from the relief valves causes large areas of dangerous ice, we do carry salt on the apparatus, but our Public Works is requested for salt trucks as well. The other concern is blown lines and or improper connections. We train often and continually remind our firefighters about proper hose connections as well as hoseline inspection. As a side note, our hoselines are pressure tested routinely by an outside vendor.

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Permalink Reply by Mark Johnson on December 3, 2008 at 1:26pm

We have static hydrant pressures of 150psi and higher throughout our fire district. These pressures are backed by massive gpm. It seems this ‘improvement’ has happened slowly over time as water mains are upgraded to larger diameter plastic pipe. However, complaining about too much hydrant pressure is almost like complaining about not being able to gain weight. Some folks might be very envious of our problems. We have a great water supply but it does create some problems. Here is a list:

Hydrants can take a little extra effort to open but not a big deal. It is important to have a good hydrant maintenance program.

We use 3” hose with 2 ½” couplings for supply. Regarding hydrant valves, we had to phase out our quarter turn ball valves as they were hard to control and dangerous with water hammer. We now use hydrant screw gates.

Opening a hydrant valve can destroy hose. As a firefighter slowly opens the valve, the first water let through at 150+ psi acts like a water jet and can cut open the hose liner. Also, the cavitation from a partially open and flowing valve will wreak havoc on the hose. To over come this, we use a piece of big, thick, heavy hose right off the hydrant valve. It holds up to abuse. The light and thin hose isn’t as tough. We also charge the line completely before the pumper takes water from the hydrant. Back pressure eliminates cavitation and makes things easier to operate.

Once the water reaches our pumps, we encounter more valve problems. We use 2 ½” intake valves both siamesed to the 6” steamer and single on the panel. It is a workout to open and close these valves and they get wobbled out over time. This is repaired fairly easily, but is a cost nonetheless. I have found no solution here yet.

Most of our equipment has an intake pressure relief valve. We set this at 150 psi which is a shame. It is set high in order to keep thousands of gallons of water from pouring onto the ground and flooding the scene. With a setting this high, however, the discharge pressure relief valve won’t work because there is not enough pressure difference from intake to discharge.

Setting up and pumping with our hydrants is not a big deal if the discharge flow is constant. We open the intake valve just enough to match the flow and give us a little extra pressure on the intake gauge. No water is lost on the ground. It is when nozzles are turned off and on that the pressure spikes, the intake relief valve opens, water pours on the ground, and suddenly all discharge gauges read 200 psi or more. A way to avoid this is to run off your tank water and only open the intake when your tank is getting low. You can finally set and use your discharge relief valve. This works on smaller fires but requires full time attention by the pump operator in order to ensure the tank doesn’t drop too low. It also requires more work by the pump motor because you are not using the pressure from the hydrant.

I better stop. I think you can probably tell that I get emotional over hot hydrants.

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Permalink Reply by JK Slupski on December 3, 2008 at 3:47pm

We have a research park w/ a looped 12" off a high-pressure 36" main. We routinely run 120 psi and have seen the system over 150 psi. The biggest issue is hydrant maintenance. A leak, such as a stuck drain, can rapidly ruin your day as the plug moves in the ground and begins to lift. These hydrants do take some work to operate but so do hydrants at lower pressures that don't see use and attention. We've seen crank-type gates stick because the pressure pins the valve. Manual gates on the apparatus can be difficult. Hooking through the steamer and the Hale MIV is definitely the way to go. Watch out when filling your tank.

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