This becomes a class 5 backflow (BFP)application. RPZ is necessary
for protecting the potable water supply.
Your system now has additives.
Is the (BFP) for the A/F loop(S) only? If it is, then a check is not
_generally_ necessary.
You need a listed expansion tank, with service valve in any case.
But, to be smart, If you have significant volume of A/F solution in the
system, you should take into account future backflow
repairs and shut off valve failures. Plus, how about forward flow test
of the BFP?
Solution to all that:
After the BFP, have a properly sized drain connection outlet with valve
with respect to the size of the service.
Make a Gauge provision, then go into a regular swing check (no hole)
to contain the A/F solution solely.
The UL expansion tank and service valve is after the swing check.
Also, another drain valve on the solution side for filling and draining.
It is more equipment, but it will save a lot of future maintenance
problems in testing and repair and not diluting the
A/F mixture. Mind you, very few people look that far ahead to the
repair issues associated with BFP's and A/F loops.
If the system side of the BFP feeds a wet sprinkler system as well as
the A/F loop, the check with hole you described,
and associated shut off and drain valves are needed. Here you need to
follow the pipe arrangements in the standard.
Mark Walker
WALKER SPRINKLER CO.
On 1/28/2017 1:43 AM, Douglas Hicks wrote:
We have a building with 2 outside canopies, each is protected by an
antifreeze loop. The sprinkler system has a backflow in a pit. Do
each of the 2 antifreeze loops need a one way swing check valve, with
a hole in the clapper? I will put a test port at each end of both
loops, even though the loops are not 150 gallons.
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