Residential Fire Sprinkler System / Private Well Water

[dpwell]

Hello,

I'm the well drilling, pump and water conditioning contractor for an under construction private residence. The water is going to require an iron removal system and softener. The fire sprinkler system connection is already installed in the interior of the house walls and is fed off the house water supply. The minimum fire sprinkler system requirement is 32 GPM @ 39.6 PSI. There is going to be too much pressure loss through the conditioning equipment to feed the fire sprinkler system. The general contractor and the fire sprinkler contractor are unwilling to separate the two and provide an exterior isolated connection for the fire sprinkler system.

I'm thinking there is likely some way to solve the problem with an isolating by-pass valve, probably about 1 1/2 inch in size. I would set the well pressure system to turn on at 50 PSI and shut off at 70 PSI. The pumping system will have plenty of capacity to feed the fire sprinkler system. I will run two lines to the house, a 1 1/4 inch conditioned water for inside and a 1 1/2 inch unconditioned for the yard. I will tie the two together and provide separation with a valve. The pilot for the valve will be connected to the house water side. If there is a 5 to 10 PSI differential on that side (should only happen in the event of the fire sprinkler system being activated) the valve will open sending unconditioned water to feed the fire sprinkler system. I talked to my valve guys at the agriculture side of Bermad and they either can't or don't want to help. Does anybody know how to set this up or can recommend a valve supplier? Attached is a sketch of my perceived layout.

Thank you for taking the time to look at this.

 

[Valvecrazy]

A simple pressure reducing valve set at 45 would work, but I don't think you have enough pump to afford the friction loss. Maybe just a regular solenoid valve like a sprinkler valve would work. Use a 45/65 pressure switch with a 24V plug in transformer to run the solenoid valve.

 

[dpwell]

Thanks Valvecrazy,

You were the one I was thinking of when I joined this forum to ask the advice. If you think that is the best approach then I guess I should starting figuring in that direction.

 

[Valvecrazy]

A pressure reducing valve set at 45 PSI would work also. But you would need a pilot operated PRV, not a direct acting PRV. You have to get like a 2" valve to be pilot operated, and it would not have the reduced pressure fall off like a smaller direct acting PRV.

 

[bimr]

It is common practice to install a bypass valve around the water softener /treatment system.

In your application, install a 1-Inch or 1- 1/2-Inch automatic solenoid valve bypass that is piped around the water softener.

Asco Valve Bypass

Use a pressure switch to activate the solenoid valve.

Low Pressure Start Switch

I would recommend that you install 120 V equipment for greater reliability.

 

[dpwell]

Good Morning,

BIMR,

I appreciate your help. Actually the Asco valve and an FSG-2 switch were my first thought. If there is a standard way of accomplishing this, that is what I want to do (especially since it is for fire protection). If I use the solenoid valve I would probably put it near the house water connection in an underground box. The original plan was to have both finished and raw water to that point. With the valve there I would like to place the switch at the well (this is where the pressure system and condition equipment will be located. I have small 24 VAC transformers that will fit in the load center. I would run power from there to the pressure switch and then on to the below grade solenoid valve.

Valvecrazy,

I see the pressure reducing valve working. I think I might add a check valve. See my attached sketch. As I mentioned though, if there is a common way to do this, that's what I want to do.

 

[dpwell]

I don't think the file is uploading properly. With the pressure reducing valve at the house the two lines are connected there, via the valve. First there's the raw water then the valve arrow pointing towards the finished water, then the check valve, again arrow in same direction. I want to place either valve at the house to avoid friction loss and high velocity through the 1 1/4 line at 32 GPM. The run from the well to the house is close to 150'. The attachment will load below.

 

[zelgar]

Is there a reason why you couldn't install a bigger pump or install a water pressure booster system?

 

[dpwell]

That was the first thing I looked at. The pump is fine, we could even go down to a 1 1/2 HP unit perhaps. The size (to limit friction loss through the filter bed & valve) and cost of the conditioning equipment is impractical.

Oh, the booster system. If there's not enough flow through the filer to start with, a centrifugal after the fact only can pull another 14.7 PSI (atmosphere) of pressure at most. Of course we could let the water flow into an atmospheric poly tank and then add another booster pump pressure system, but that gets even more costly and complicated. I like my atmospheric tanks for potable water maintaining chlorine residual.

 

[Valvecrazy]

The check valve will just cause extra restriction. A pressure reducing valve without a thermal bypass will act like a check valve anyway, so I wouldn't use a check valve. A pilot operated pressure reducing valve will have maybe 15 PSI friction loss, which may require a larger pump. The solenoid valve will also work like a check valve and will not have as much friction loss as a pressure reducing valve, so will work with smaller pump.

 

[itsmoked]

I'm surprised. Around here you must have stored water in a tank for fire if you're on a well of any kind and you'd also not be allowed to interconnect raw and finished water in any way. Are you sure this cheap-o-plan is permitted?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

Keith, that would be the case only if the "raw" water is non-potable.

 

[itsmoked]

Ah, Thanks Comp.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[bimr]

I believe the best option is to make this as simple as possible.

There is no need for pressure reduction or a check valve. Just use a standard solenoid valve which will isolate the two systems unless the water flows into the fire line. Use a solenoid valve with a slow closing feature to avoid water hammer. I would wire this system with equipment that is rated for 120 Voltage as it will be more reliable. That will require just one separate 120 V circuit in the panel box.

On second thought, I believe a water flow detector switch installed in the fire line will be a better option than a pressure switch. The pressure switch would probably cycle on/off as the solenoid valve opens and closes.

If you have a water flow detector switch in the fire line, the water flow detector switch can open the solenoid when water is flowing into the fire line. At all other times, the solenoid valve will remain closed.

water Flow Detector for fire line

Note that none of this including the well will work should the power fail.

 

[dpwell]

I appreciate everyone's input. I've had requests in at Flomatic and Cla-Val, but haven't heard back from either. The house is almost completed and I don't want to be the final holdup. BIMR suggests and Valvecrazy concurs the pressure switch controlled solenoid valve is the correct course (it was my initial thought too). I think the body of the solenoid valve has to have NSF approval for potable water, exempli gratia, lead free brass, stainless steel or poly. If I don't hear anything by morning I'm going to contact Asco and see what they suggest. I still have to quote the add-on and get approval from the local jurisdiction. I'll reply to this thread as how it turns out.

 

[dpwell]

Nice catch on the pressure switch operation. I'll have to consider that. The paddle switch isn't going to work because I can't get to the fire line (it's in the wall).

 

[dpwell]

I want to use 24 VAC because I want to install the solenoid valve below grade remote from the well. If the valve box were to fill with water I don't want 120 VAC present. The load center is going to be outside (if a well house is built) on a post. I figure I can install a red panel light on the load center that connected to a normally closed single pole relay with 24 VAC coil continuously energized by the transformer. The panel light lamp would be 120 VAC. That way the light would glow red if the transformer failed. I can put a description nameplate below the panel light. I think I can solve the pressure switch problem by setting the cutout pressure above the capacity of the pump with the fire sprinklers on. I believe Asco also makes a pressure switch that can be adjusted to a narrower or wider differential than the Pumptrol switch is capable. I'll ask about the slow closing solenoid and the pressure switch as well.

 

[Valvecrazy]

I find a pressure switch to be much more reliable than a flow switch. And the pressure switch will not cycle as long as the sprinklers put out more volume than the pump can produce at 65 PSI. Also the sprinkler solenoid valves I use are plastic (no lead). A sprinkler valve with a flow control knob can be set to not go all the way open, so it won't water hammer on closing even though it doesn't have a closing speed adjustment. A sprinkler valve will be about 30 bucks, where a metal solenoid valve with NSF61G and speed control will be several hundred bucks.

 

[dpwell]

I agree on the paddle flow switches. It seems like they're often stuck in the on or off position. I have one that works like a engine's mass air flow sensor, but the timers and relays to make it function are complicated. I have a message into one of my irrigation suppliers about the sprinkler valve without a manual shut off. The fire inspector doesn't seem to like the option of shutting off the fire sprinkler line without shutting off all the water.

 

[dpwell]

Here's the county's response.

"Mike, Unfortunately I have 2 problems with your system. First the solenoid valve is not part of an approved Fire sprinkler system as per NFPA 13, Secondly who would be liable if the solenoid system failed?"

The inspector has the link to this forum.

Attached is my pressure switch - solenoid valve sketch.

http://files.engineering.com/getfil...d-7ce56b079c5e&file=Solenoid_Valve_Layout.jpg