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TeaMan

Active Member

1

Saturday, September 10th 2011, 9:46pm

Watts RPZ devices

Does anyone know the difference between a Watts 919 and a Watts 009 RPZ device. I can't seem to be able to find much of any information on the Watts 919 online, even a place to buy one, but the local plumbing shop said it's the one his supplier has. I can find lots of info on the Watts 009 and online sources. The cost of the 919 is significantly higher than the 009.
Any ideas?
TeaMan

Wet_Boots

Supreme Member

Posts: 4,044

Location: Metro NYC

2

Sunday, September 11th 2011, 11:09am

the Watts 919 resembles the Conbraco RPZ, but does not have the testcock on the lower section, so some disassembly will be required when winterizing.


TeaMan

Active Member

3

Sunday, September 11th 2011, 2:00pm

Would you say that functionally they are equal as far as protection? Seems to me that if they are, and the 919 requires disassembly to winterize, then the 009 would be the better, especially since it's significantly less expensive.
Would the 919 just be older technology and the 009 newer?

Wet_Boots

Supreme Member

Posts: 4,044

Location: Metro NYC

4

Sunday, September 11th 2011, 3:30pm

the "older technology" may have a functional advantage when supply pressures are lower (around 50-60 psi)

TeaMan

Active Member

5

Monday, September 12th 2011, 10:50am

That worries me a bit, my pressure is 60 psi at the supply which is pretty good for my area. In other posts I had researched, I thought I saw problems around 20 psi so I thougth I'd be OK. Would you not recommend the 009 for pressures around 60 PSI? I had to put pressure reducing valves in to reduce to 40 and 30 PSI for proper head function according to my Rainbird design, so I thought I'd be OK with the pressure I have. As I say, this worries me a bit. Problems I don't need.

Maybe there is a better brand than the watts? I know it's subjective, but experience does play a roll here....

Thanks for the advice...

HooKooDooKu

Supreme Member

6

Monday, September 12th 2011, 12:35pm

The combination of a 60psi water supply and an RPZ should mean that you don't NEED pressure reducing anything.

The RPZ itself is going to cause 10 to 15 psi pressure loss. Your valves will likely add another 3 to 5. When you tack on the pressure losses of the meter, the water pipes, and changes in evelvation, you're likely to have around 40 psi of pressure at the heads (a good number).

The only place I would consider any sort of pressure control is if you want to get the 1800 series of Rainbird Popups with the built-in PRS (Pressure Regulating Stem). The PRS is built into the pop-up, and sets the output pressure to 30 psi. And the only reason you would need the PRS is if you want the performance of the nozzles to be the exact same from one location to the next (something that might be needed or desired with large swings of elevation or distance).

I would suggest that you not get pressure reducing valves and instead get valves with flow control and Popus with PRS built into them (neither is a MAJOR cost relative to "basic" features). The flow control will give you some control over the relative pressure IF you should need it, while the PRS will provide the constant nozzle performance.

TeaMan

Active Member

7

Monday, September 12th 2011, 1:57pm

My mistake totally, my valves are flow control, not pressure control. I had pressure on the brain obviously. They are CPF-100's. My GPM at the exit of the house to the sprinklers is about 32 GPM and rainbird designs for 21 GPM so they designed the flow reduction valves.

My elevation differences in 3 of my zones is about 4 feet. I should be able to adjust any problems out of the system. It doesn't have to be perfect. My heads are 42SA+, 32SA and surepop 600's such as the SP40H.
Good advice on the pressure. I was reading more on the RPZ's and saw they have a large pressure drop across them. I guess I'd consider 15PSI fairly large, but it does as you said put me right about in range for the design so it works out pretty well.

Any ideas as to what to do with the model of RPZ? I'm OK for testing since I put a manual valve between the house and sprinkler and am using is during testing to isolate the house from the system, no backflow.

TeaMan

Wet_Boots

Supreme Member

Posts: 4,044

Location: Metro NYC

8

Monday, September 12th 2011, 2:12pm

Stop what you are doing and install the RPZ. Now. Not later.

HooKooDooKu

Supreme Member

9

Tuesday, September 13th 2011, 12:07pm

What Boots said...

Even a manual control valve MUST be protected by some form of Backflow protection. After all, even if you are using a hose spigot (where when the water is off, backflow is impossible since the valve is absolutely shut), there is the possibility of an event that could cause backflow while the valve is open. In that case, the water company could start sucking water from your "testing" equipement back into the water supply.

As for which RPZ, unless your local building athority specifies a particular part number they require for backflow protection, pretty much every RPZ is going to be bomb proof as far as protecting the water supply. So you might as well use the cheapest option.


Otherwise, on the subject of should you use the 009 or the 919, from what I see looking at the devices and reviewing the specification sheets, the 919 seems to be ment for an industrial setting where it gets heavy use and needs frequent maintainence. By contrast, the 009 seems to be ment for less heavy utilization. Otherwise, the level of protection offered by each is the same. Since you're NOT going to be pumping 20gmp 24/7 through this device, I think the 009 will more than suit your needs. (No need to buy a tank to do some off-road driving when an SUV will do the job just fine)

Wet_Boots

Supreme Member

Posts: 4,044

Location: Metro NYC

10

Tuesday, September 13th 2011, 3:34pm

Besides the obvious backflow issue, there is the issue of wasting time. Complete the plumbing, including the RPZ, then worry about the system, because only then do you know what the available flow and pressure will be.

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