I believe its ratio based.  Not sure on the Viking but the Reliable DDX-LP has 
a 15 psi air at 100 psi water.

From: Fpdcdesign <[email protected]>
Sent: Tuesday, March 3, 2026 9:47 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]>
Subject: [Sprinklerforum] Re: CPVC in dry system

JD, that k you for the information. When is says “…pressure doesn’t exceed 15 
psi…”, does that mean air pressure, water pressure or both?

Todd G Williams, PE
Fire Protection Design/Consulting
Stonington, CT
860-535-2080<tel:860-535-2080> (ofc)
860-554-7054<tel:860-554-7054>  (fax)
860-608-4559<tel:860-608-4559> (cell)



On Mar 3, 2026 at 11:32 AM, <JD Gamble<mailto:[email protected]>> wrote:
Consider a Low Pressure Dry Pipe System
Unlike wet systems, dry pipe systems aren’t prone to freezing because the pipe 
is not filled with water. Instead, it’s filled with pressurized air or nitrogen 
that keeps the valve to the water supply closed. When a sprinkler head 
activates, the air pressure in the system drops, causing the valve to open and 
releasing water into the pipes to be delivered to the fire sprinkler heads.
Tyco (Johnson Controls) and Viking BlazeMaster pipe is UL listed for use in 
Light Hazard and Residential dry pipe sprinkler systems where the pressure 
doesn’t exceed 15 psi and the ambient temperature is above -20ºF (-29ºC). A dry 
pipe system utilizing BlazeMaster CPVC must be designed to provide pressure 
relief when the system pressure exceeds 15 psi. Alternatively, the system may 
be equipped with an alarm that sounds when the pressure exceeds 15 psi. Other 
design and installation parameters are outlined in the manufacturer’s 
installation guide. A link to Tyco’s is 
here<https://docs.johnsoncontrols.com/tycofire/api/khub/documents/Y7NN9_1q7PoIN9081~sZ9Q/content>,
 and Viking’s is 
here<https://www.vikinggroupinc.com/sites/default/files/documents/080712.pdf?__hstc=120511383.ac16f0333100f67a732406dc8ddd60c5.1668094726860.1700233678466.1700494728935.153&__hssc=120511383.1.1701212585389&__hsfp=1999393944&hsCtaTracking=b491017c-9540-4865-90>.
A key benefit to using BlazeMaster pipe in a low pressure dry system is that 
BlazeMaster CPVC is naturally resistant to corrosion and microbiologically 
influenced corrosion (MIC), completely eliminating the corrosion concerns, and 
the associated maintenance costs, that plague metallic dry systems.

From the BlazeMaster Website


From: Patrick Tomaszewski 
<[email protected]<mailto:[email protected]>>
Sent: Tuesday, March 3, 2026 9:28 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: CPVC in dry system

Never heard of this.
Ive only ever seen standards and manufacturers documentation saying that CPVC 
products are approved for wet systems only.

Maybe instead of telling him no, you can ask client to produce the 
documentation saying it is acceptable – we can do whatever the client wants as 
long as it complies with codes, standards, manufacturer’s docs, and AHJ 
approval.

That way you don’t have to risk being wrong, while maintaining compliance based 
on your own knowledge.

[signature_2544299208]
Patrick tomaszewski | Estimator
www.valiantfireco.com<http://www.valiantfireco.comorg>
[email protected] <mailto:[email protected] >
📍3910 Howe rd. Wayne, MI 48184
“Every Second Matters.”
IG<https://www.instagram.com/valiantsec.mi/> • 
FB<https://www.facebook.com/valiantsec.mi> • LINKED 
IN<https://www.linkedin.com/company/valiant-security-llc>


From: Fpdcdesign <[email protected]<mailto:[email protected]>>
Sent: Tuesday, March 3, 2026 11:21 AM
To: Sprinklerforum 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] CPVC in dry system

I had a client tell me this morning that there was something about CPVC being 
approved for residential dry systems where low pressure dry valves were used. I 
have never heard of it and can’t find any references about it. Before I tell 
him no, is there something that I am missing?

Todd G Williams, PE
Fire Protection Design/Consulting
Stonington, CT
860-535-2080<tel:860-535-2080> (ofc)
860-554-7054<tel:860-554-7054>  (fax)
860-608-4559<tel:860-608-4559> (cell)
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