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Thread: Supplying an aerial with a 2.5in discharge from an Engine

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    Default Supplying an aerial with a 2.5in discharge from an Engine

    I am new to this, so please help me out here. I have read a few previous posts and I have already received more information about this topic than I ever thought. My question has still only been partially answered.
    My question is based on a previous incident at a fire. It is about GPMs supplied to the aerial. We used a single 2.5 in., 30 degree elbow discharge on a 1,250 GPM single stage pump. Connected to the 2.5in. discharge was an adapter (2.5in. to 5in., stortz) followed by 100 ft of 5in. LDH. This is what supplied the aerial. The water supply was 800ft. of 5in. LDH hooked up to the steamer cap of a hydrant capable of flowing 1,499 GPMs, as the color coding goes (green bonnet). There was no relay pump and the elevation increase was less than 10 feet.
    I am in the belief, and maybe wrong, that greater gallonage to the aerial could have been accomplished using 2 discharges instead of one. Here is the difference though. I believe using 2 2.5in. discharges with 50 or 100ft. (negligable) of 2.5in hose into a Siamese (2.5in to 5in.) on the LDH intake of the pump of the aerial. the aeriel was close enough to the primary pumping engine to use 50ft. of hose. I recognize there is greater friction loss to overcome on the 2.5in hose. Both set ups have adapters that should cancel each other out.
    The previous posts I have read were based on a hydrant to pump. This is pump to pump. I am not sure what the primary pump set the discharge supplying the aeriel to and the aerial was set to 150psi at its pump. No other hoses were flowing on either apparatus at the time. Can anyone help me out?


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    to clarify the previous post, the primary pumping apparatus does not have an LDH discharge on it. Thanks.

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    You are correct in your thinking that two discharges would pump the single 5" line more efficently (especially with a single stage pump). We got rid of a 1978 Hahn a few years back with a 1250 that did not have a 5" discharge; we had two 6' lengths of 3.5" hose specially made and fed them into a gated wye that we "gutted" to decrease the friction loss. That was our standard 5" "discharge."

    You are limited in what the pump can push through a single 2.5" discharge. Modern pumps that have a 5" discharge are almost always of the "pantleg" design- two 3" lengths of pipe bent and welded into a singe 5" discharge, and usually (not always) controlled with two valves.
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    2.5" discharge with a 5" adapter is very common in my area. We've never had one, but I have seen many on trucks in the area. We did have a 5" stortz adapter on the rear of 1 engine, but it was plumbed with a 3" line.
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    As stated above you can only push so much water through a given diameter

    Check out your theory

    Have both set ups and use straight bore and pitot, to see what flows you get out of each set up



    http://www.flowbuster.com/uploads/FL...ed_4-10-09.pdf
    Last edited by fire49; 01-14-2013 at 11:14 PM.

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    If that 2 1/2 discharge comes straight off the pump manifold it is entirely possible to flow over 1000 GPM through a single 2 1/2 discharge. In fact we used to do it off from our second out engine with an adapter to 5 inch on a single 2 1/2 discharge.

    I am always amazed at people saying it is not possible to do that through a single 2 1/2 when we can flow in excess of 1650 gpm through a 2 1/2 deluge nozzle tip at 80 PSI.
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    Quote Originally Posted by FyredUp View Post
    If that 2 1/2 discharge comes straight off the pump manifold it is entirely possible to flow over 1000 GPM through a single 2 1/2 discharge. In fact we used to do it off from our second out engine with an adapter to 5 inch on a single 2 1/2 discharge.

    I am always amazed at people saying it is not possible to do that through a single 2 1/2 when we can flow in excess of 1650 gpm through a 2 1/2 deluge nozzle tip at 80 PSI.
    Especially when you realize that the entire capacity of a 1500 GPM pump passes through two cutwaters the size of your thumb.

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    Quote Originally Posted by FyredUp View Post
    If that 2 1/2 discharge comes straight off the pump manifold it is entirely possible to flow over 1000 GPM through a single 2 1/2 discharge. In fact we used to do it off from our second out engine with an adapter to 5 inch on a single 2 1/2 discharge.
    Yes indeed it is possible.....However to flow more water more efficiently at lower pressures, better to siamese out of two discharges. Nothing like getting a headache after standing at a pump panel pushing water into a 5" line through one 2.5" discharge for three hours- especially if the pumper has a loud, obnoxious, smoke-blowing, oil-dripping 2-cycle wanna-be a Lawn Boy mechanical azzhole under the hood.......
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    Quote Originally Posted by FWDbuff View Post
    Yes indeed it is possible.....However to flow more water more efficiently at lower pressures, better to siamese out of two discharges. Nothing like getting a headache after standing at a pump panel pushing water into a 5" line through one 2.5" discharge for three hours- especially if the pumper has a loud, obnoxious, smoke-blowing, oil-dripping 2-cycle wanna-be a Lawn Boy mechanical azzhole under the hood.......

    How is it any different than standing at the pump panel pushing 1000 gpm through an engine mounted deck gun with a single 2 1/2 or 3 inch pipe feeding it?
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    It's all about the friction loss - and the friction loss in a few feet of pipe isn't all that bad. If you told me you were trying to pump 1000 gpm to the aerial through 800 feet of 2.5" or 3", I'd have serious doubts.

    We carry an LDH fitting on a 2.5" discharge, and have used it to flow everything the pump will give, depending on what's coming in.

    That said - a discharged suitably plumbed for LDH discharge isn't a bad feature to include on an engine if you're going to be doing it frequently.
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    Have you considered using a siamese, or water thief?
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    You could run two 3 inch lines from two 2.5 inch discharges and feed a single 5 inch line to supply the aerial.

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    mebmikec: Please either open an access door on the officer's side of the engine or get a creeper and a light from underneath. Try to determine the outlet with the LEAST number of elbows. Also look at the discharge valves to determine if they are 2" ball openings on a 2 1/2" frame, 2 1/2" full flow valves, or 3" full flow valves and 2 1/2" piping. Some older Hales used 2" valve balls and are not suitable to supply large flows. If you are familiar with friction loss formulas or tables, it is possible to make an estimate of friction loss as follows: For a 2 1/2" valve with 2" waterway = 30 ft of 2 1/2" hose; For a 2 1/2" valve with 2 1/2" opening = 10 ft; A 3" valve with 3" opening = 6 ft. For every 90 deg. elbow = 15 ft. for a 45 deg. elbow = 6 ft.
    Example: Hale usually has a manifold across the top of the pump that splits on the officers side (two 45 deg. elbows and a 2 1/2" valve) Discharge from the pump body comes vertically into the manifold (90 deg) and you have a 45 deg. droop snoot on the outlet. (90) 15 + (45) 6 + (45) 6 + (valve) 10 + (45) 6 + (pipe run) 6 = 49 ft. or 1/2 of a section of 2 1/2" hose. Expect the following losses inside the pump house: At 500 gpm = 5 * 5 * 2.5 * 1/2 = 31 psi. Trying to flow 800 gpm (1 3/4" tip) = 8 * 8 * 2.5 * 1/2 = 80 psi. So 800 gpm is doable for this engine. Trying to stretch things to 1,000 gpm we get 10 * 10 * 2.5 * 1/2 = 125 psi. plus hose loss of 6 psi +
    Second problem will be over pressure on the LDH if the aerial shuts down. Dangerous.
    I would be more concerned with the forward lay that you describe. Understanding the hydrant color code conditions is more critical than discharging water to a quint. What the color code says is ... You have 1500 gpm available, but it may be as low as 20 psi. 1500 gpm needs 15 psi per 100 ft. of 5" to move the water. To deliver the 1500 gpm on a 1,000 ft. forward lay, the hydrant would need a FLOWING pressure of 150 psi. NOT LIKELY. Suppose the static hydrant pressure was 80 psi & the residual was 20 psi at 1500 gpm. (60 psi distribution grid piping loss) .... Then at 750 gpm the residual hydrant pressure would be 65 psi. (1/4 the loss at 1500) 750 gpm through 5" hose has a Fl of about 4 psi./100 ft or 40 lb loss in the hose. Incoming at the engine would be 25 psi. (is this where you are taught to stop throttling up?)
    In this case the flow would be limited to about 750 gpm. By dropping a hydrant assist valve and picking it up with a second engine, you could take advantage of the full hydrant flow of 1500 gpm, but only if you hooked up a second line from the engine to the aerial. Stuffing 1500 gpm through the single outlet would result in 15 * 15 * 2.5 * 1/2 = 281 psi. loss in the pump house. Adding a second output to the aerial the discharge loss drops to 140 plus 15 for loss in the 100 ft. of LDH and 20 incoming to the Quint = 175 psi. OK for the LDH supply line at 180 psi max, and the engine is able to take advantage of the incoming 20 psi allowing the 1500 to actually pump 1500 at 175 psi.

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    Quote Originally Posted by kuh shise View Post
    mebmikec: Please either open an access door on the officer's side of the engine or get a creeper and a light from underneath. Try to determine the outlet with the LEAST number of elbows. Also look at the discharge valves to determine if they are 2" ball openings on a 2 1/2" frame, 2 1/2" full flow valves, or 3" full flow valves and 2 1/2" piping. Some older Hales used 2" valve balls and are not suitable to supply large flows. If you are familiar with friction loss formulas or tables, it is possible to make an estimate of friction loss as follows: For a 2 1/2" valve with 2" waterway = 30 ft of 2 1/2" hose; For a 2 1/2" valve with 2 1/2" opening = 10 ft; A 3" valve with 3" opening = 6 ft. For every 90 deg. elbow = 15 ft. for a 45 deg. elbow = 6 ft.
    Example: Hale usually has a manifold across the top of the pump that splits on the officers side (two 45 deg. elbows and a 2 1/2" valve) Discharge from the pump body comes vertically into the manifold (90 deg) and you have a 45 deg. droop snoot on the outlet. (90) 15 + (45) 6 + (45) 6 + (valve) 10 + (45) 6 + (pipe run) 6 = 49 ft. or 1/2 of a section of 2 1/2" hose. Expect the following losses inside the pump house: At 500 gpm = 5 * 5 * 2.5 * 1/2 = 31 psi. Trying to flow 800 gpm (1 3/4" tip) = 8 * 8 * 2.5 * 1/2 = 80 psi. So 800 gpm is doable for this engine. Trying to stretch things to 1,000 gpm we get 10 * 10 * 2.5 * 1/2 = 125 psi. plus hose loss of 6 psi +
    Second problem will be over pressure on the LDH if the aerial shuts down. Dangerous.
    I would be more concerned with the forward lay that you describe. Understanding the hydrant color code conditions is more critical than discharging water to a quint. What the color code says is ... You have 1500 gpm available, but it may be as low as 20 psi. 1500 gpm needs 15 psi per 100 ft. of 5" to move the water. To deliver the 1500 gpm on a 1,000 ft. forward lay, the hydrant would need a FLOWING pressure of 150 psi. NOT LIKELY. Suppose the static hydrant pressure was 80 psi & the residual was 20 psi at 1500 gpm. (60 psi distribution grid piping loss) .... Then at 750 gpm the residual hydrant pressure would be 65 psi. (1/4 the loss at 1500) 750 gpm through 5" hose has a Fl of about 4 psi./100 ft or 40 lb loss in the hose. Incoming at the engine would be 25 psi. (is this where you are taught to stop throttling up?)
    In this case the flow would be limited to about 750 gpm. By dropping a hydrant assist valve and picking it up with a second engine, you could take advantage of the full hydrant flow of 1500 gpm, but only if you hooked up a second line from the engine to the aerial. Stuffing 1500 gpm through the single outlet would result in 15 * 15 * 2.5 * 1/2 = 281 psi. loss in the pump house. Adding a second output to the aerial the discharge loss drops to 140 plus 15 for loss in the 100 ft. of LDH and 20 incoming to the Quint = 175 psi. OK for the LDH supply line at 180 psi max, and the engine is able to take advantage of the incoming 20 psi allowing the 1500 to actually pump 1500 at 175 psi.
    How do you over-pressure the LDH if: 1) The intake for the aerial has a relief valve on it, 2) You have the pressure governor set on the supplying engine?
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    Not sure I understand the warning about overpressurzing the LDH either. When we are feeding the aerial with enough pressure worry about possible overpressure we are feeding into the back of the truck. So the supply engine controls the water flow to the platform. In the event we were performing a normal relay (aerial pump supplying pressure to the platform) the pressures would be so low that it would matter if the flow was shut down.

    The only area we have run into problems as far as pressure goes is with long lays when feeing the platform from the supply engine. We test our LDH to 200 PSI and it is not hard to exceed that when you figure a 175 PSI pressure required at the truck, plus friction loss of the line.
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    FyredUp & GTRider: The reason for caution flagging this operation is for the following reasons. The layout has a significant amount of mass (water weight might be considerably more than 7,500 lbs) moving at a velocity (7 to 15 mph). If a basket operator were to shut down the nozzle, without the customary throtteling down of the relay engine the velocity head can and will create very large spikes in pressure. A relay relief valve has a finite pressure - volume response curve that creates back pressure when a high volume of water must pass through the dump valve. Second, many if not most newer engines are using pressure governors that require a finite response time (2 to 5 seconds) before shut down or throttle back occurs. Some fire departments, because of high hydrant pressures, set their relief valve at 150 psi and above. This severely limits the effectiveness of the relief, allowing only 30 psi drop across the dump between the normal 150 and the relief protection value of 180 psi. While you gentlemen make it a policy to do annual service pressure tests on hose, some departments reading this might not. Just trying to protect someone from themselves.

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    Quote Originally Posted by kuh shise View Post
    FyredUp & GTRider: The reason for caution flagging this operation is for the following reasons. The layout has a significant amount of mass (water weight might be considerably more than 7,500 lbs) moving at a velocity (7 to 15 mph). If a basket operator were to shut down the nozzle, without the customary throtteling down of the relay engine the velocity head can and will create very large spikes in pressure. A relay relief valve has a finite pressure - volume response curve that creates back pressure when a high volume of water must pass through the dump valve. Second, many if not most newer engines are using pressure governors that require a finite response time (2 to 5 seconds) before shut down or throttle back occurs. Some fire departments, because of high hydrant pressures, set their relief valve at 150 psi and above. This severely limits the effectiveness of the relief, allowing only 30 psi drop across the dump between the normal 150 and the relief protection value of 180 psi. While you gentlemen make it a policy to do annual service pressure tests on hose, some departments reading this might not. Just trying to protect someone from themselves.
    My career FD does not buy any LDH that does not meet 250psi usage pressure. It is sometimes called attack LDH.
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    Just to reinforce what kuh shise said, if I did my math right some time back, a length of 5" will hold ~100 gallons of water, for something over 800 pounds. As kuh shise notes, the water is moving at considerable speed, all things considered. I calculated that at 1000 GPM that would be about 11 MPH. A sudden stop certainly raises the possibility that something is going to give. Hopefully it's the relief valve, and not the hose, or perhaps even an undetected flaw in the downstream pump.

    Remember that incident where a manifold blew not that long ago.

    The "seat belt convincers" that our cops use only reach a speed of 5-10 MPH (and I think it's closer to 5 than 10) and that sudden stop will put an unbelted person on their nose.
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    We solve this entire issue by letting all water flow control to the platform be in the hands of either the relay pump operator or the pump operator of the aerial truck when using a quint. The crew in the platform never shuts off water flow from there.
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    Quote Originally Posted by NOVA_Fireman View Post
    Have you considered using a siamese, or water thief?
    Attachment 22700

    You could run two 3 inch lines from two 2.5 inch discharges and feed a single 5 inch line to supply the aerial.
    That is how several of my previous departments have pumped 4' or 5' without the benefit of an LDH discharge.

    We have also pumped it from a single 2 1/2' discharge as well with some pretty reasonable flows.
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    goodmorning, I may not have been clear on the original post. My theory was 2 lines (2.5in. coming off 2 2.5in. discharges), length at most 100ft. of hose going straight into aerial pump via a 2.5in. to 5in. siamese. I feel that the short length would require less than 100psi at the pump to supply aerial at least 1,000GPM. The original connection was a single 2.5in. discharge with an adapter into a 100ft. section of 5in. straight into the aerial's master intake. I am glad that others are sharing similar opinions, ideas and options. With that said, I am learning the original hook up wasn't as bad as I had previously thought. Thanks.

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