NFPA guidelines for installing components that supply and maintain pressurized air to dry sprinklers

A reliable and by rights maintained add of pressurize air is key to the dependable mathematical process of dry sprinkler systems. But the extra equipment needed to achieve optimum levels makes facility more time-consuming and complex .
In this mail, we will take a look at best practices for installing the unique components of a dry sprinkler system that issue and maintain the pressurize air in the pipes .
Check out previous installments in the series:
A Guide to Dry Sprinkler Systems, Part 1 : system Overview

A Guide to Dry Sprinkler Systems, Part 2 : Components and initiation Requirements
A Guide to Dry Sprinkler Systems, Part 3 : installation of Components
Are you looking to buy parts for your build ’ second sprinkler system ? QRFS offers a range of dry sprinkler heads available on particular order. Simply give us a call at 888.361.6662 or email [ e-mail protected ] .
You can besides view our in-stock survival of sprinkler gauges, valves, supervisory switches, and early accessories .

Extra parts make installation of dry systems more complicated

Dry sprinkler systems are used when the pipe in a wet sprinkler system can ’ thymine be heated to prevent freeze, risking blocked or burst pipes that would render the wet system inoperable. Dry sprinkler systems are filled with supercharge atmosphere or nitrogen until the hotness from a open fire opens a sprinkler head. When that occurs, the loss of tune pressure in the piping causes a special dry valve to tripper, releasing water into the pipes and out the open sprinklers onto the ardor .
Filling the system with supercharge air that won ’ thyroxine induce the pipes to freeze in cold temperatures requires supernumerary components not found in wet systems – and NFPA 13 : standard for the Installation of Sprinkler Systems sets rigid guidelines for installing these parts to ensure the systems work angstrom intended. Let ’ s take a look at some of the main air issue components and NFPA ’ sulfur facility requirements .

Dry sprinkler components that maintain air pressure and supply

NFPA 13 defines its use of “ vent ” as air, nitrogen, or other approve gases for a dry sprinkler system. The air issue must come from a dependable generator, and A. permits it to be “ generated on-site or from storage containers sized to provide a authentic add for at least 6 months of expected alimony use. ” These gas-storage containers besides must have a low-pressure alarm that alerts property owners when they need to be refilled ( ) .
While air supplies may be provided by plant vent systems, most often an atmosphere compressor feeds clean, dry, supercharge air travel or nitrogen into the arrangement. The amount of breeze pressure needed to keep the dry valve from opening must be maintained on dry sprinklers at all times until the system is activated ( ). How much and how long the compressor runs directly relates to the amount of escape in the system – often a mastermind result of how tightly fittings are installed .
NFPA 13 offers the take after guidelines for air out leaks :

From the 2019 Edition of NFPA 13 The allow rate of air escape shall be as specified in 28.2.2, which details the dry pipe and double mesh preaction arrangement air screen . In accession to the standard hydrostatic test, an atmosphere imperativeness escape test at 40 psi ( 2.7 prevention ) shall be conducted for 24 hours. Any escape that results in a loss of pressure in excess of 1 ½ psi ( 0.1 bar ) for the 24 hours shall be corrected . Where systems are installed in spaces that are adequate to of being operated at temperatures below 32°F ( 0°C ), air or nitrogen gas pressure escape tests required in 28.2.2 shall be conducted at the lowest nominal temperature of the distance . Pipe or tube specifically investigated for suitability in dry pipe and double interlock preaction organization ( s ) and listed for this service, shall be permitted to be tested in accordance with their list limitations .

Smaller sprinkler systems may use riser-mounted compressors to combat minor leaks, which are less expensive but tend to be noisier than tank-mounted compressors. Tank-mounted compressors besides have downsides to consider – including higher costs and a want for extra floor space – but are preferable for most applications .
here ’ mho why : The tank acts as a supercharge reserve with a larger capacity, reducing the frequency that the compressor needs to run to supply the system. Lower ambient noise is another benefit, as mounting the compressor to the tank vibrates the cooler alternatively of the build ’ south piping. In fact, General Air Products recently released a “ Quiet Series ” tank-mounted compressor to further reduce noise complaints .
Tank-mounted air compressor
NFPA 13 doesn ’ t distinguish between types of compressors, but it does require the compressed air provision to come from a source that ’ randomness always available ( ) and can restore normal air travel pressure to the sprinkler arrangement within 30 minutes ( ). The sole exception : compressors that help protect refrigerate spaces maintained below 5°F ( –15°C ), where normal system publicize pressure can be restored within 60 minutes ( ) .
NFPA 13 besides offers facility guidelines for the vent supply connections that link the air travel compressor to the dry valve. Installers should use the character of connection recommended by the manufacturer and approved by the agency having jurisdiction, while considering the pressures, temperatures, and vibrations that the connections and its adjacent equipment weather. A. says flexible hoses may be desirable that are adequate to of withstanding the expect vibration, maximal pressure of 75 psi or greater, and a utmost temperature of 150°F ( 66°C ) or higher .
other initiation requirements include :* The connection from the air supply to the dry pipe valve shall not be less than 1∕2 in. ( 15 millimeter ) in diameter and shall enter the arrangement above the prim water level of the dry pipe valve. A assay valve shall be installed in the air filling connection . A list or approved shutoff valve of either the renewable disk or ball valve type shall be installed on the provide side of this check valve .

NFPA 13 ( ) besides calls for the initiation of an approved relief valve between the vent provision and shutoff valve that ’ sulfur “ set to relieve atmospheric pressure no less than 10 psi ( 0.7 cake ) in overindulgence of arrangement air pressure provided in and shall not exceed the manufacturer ’ mho limitations. ”
easing valves alleviate surfeit pressure due to electric potential thermal expansion issues. Relief valves that are approved, or “ listed, ” are tested and certified to UL 1478A .

Proper installation of automatic air maintenance devices prevents accidental triggers

Automatic atmosphere maintenance devices are essential for maintaining proper air blackmail in dry sprinkler shoot. Installed downriver from the air compressor, they reduce the possibility of false valve trips due to tiny leaks that slowly reduce a dry system ’ s air atmospheric pressure by providing a continuous but restricted air out issue to the pipes. They besides ensure the blackmail doesn ’ deoxythymidine monophosphate climb besides high, which can damage the dry valve and prevent it from opening during a open fire .
The tune alimony device mechanically causes the air compressor to cut in and out to achieve the properly libra. It prevents the air supply from adding vent at excessively fast a rate, which could stop the dry valve from releasing the urine during a fire .
NFPA 13 requires every dry arrangement to have a dedicated air maintenance device ( ) listed by Underwriters Laboratories ( UL ) . Where stored nitrogen or other approved gasoline is used, the flatulence shall be introduced through a press regulator and shall be in accordance with .

Tyco AMD
NFPA 13 offers the follow guidelines for atmosphere sustenance device facility :* Unless the requirements of are met, where the air supply to a dry pipe system is maintained mechanically, the air supply shall be from a dependable plant system or an vent compressor with an air receiver, and shall utilize an air care device specifically listed for such service and capable of controlling the ask tune press on, and maximum airflow to, the dry organ pipe arrangement . Where the air compressor supplying the dry pipe system has a capacity less than 5.5 foot 3/min ( 160 L/min ) at 10 psi ( 0.7 bar ), an air telephone receiver or breeze alimony device shall not be required . The automatic air add to more than one dry pipe arrangement shall be connected to enable individual maintenance of breeze coerce in each system . A check valve or other convinced backflow prevention device shall be installed in the air provide to each system to prevent airflow or waterflow from one system to another . Where an air compressor is the dedicated breeze supply, it shall be installed in accordance with NFPA 70, Article 430 . The unplug means for an automatic air out compressor shall not be a general-use easy switch or a cord-and-plug machine-accessible centrifugal .

Reliable air pressure is essential in dry sprinkler systems

In order to operate faithfully, dry fire sprinkler systems require a uninfected, dry supply of air or nitrogen that ’ s carefully maintained at the proper blackmail. By taking the time to understand NFPA requirements and installing these devices correctly, you can ensure that your dry system stands ready to protect people and property from fires in freezing temperatures .
Stay tuned for the adjacent installments in our review of dry sprinkler systems and their applications, in which we ’ ll research inspection, testing, and alimony requirements, including an in-depth look at how to prevent corrosion. meanwhile, make sure to view former blogs in the series :
A Guide to Dry Sprinkler Systems, Part 1 : system Overview
A Guide to Dry Sprinkler Systems, Part 2 : Components and Installation Requirements

A Guide to Dry Sprinkler Systems, Part 3 : initiation of Components
If you ’ re looking to buy components for your dry pipe sprinkler system, QRFS offers a stove of dry sprinkler heads available on special order. Simply give us a call at 888.361.6662 or email [ electronic mail protected ] and we ’ vitamin d be glad to help .
We besides stock certificate sprinkler gauges, valves, switches, and early accessories that work in dry systems .

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