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#125 - A Guide to Inspecting Fire Sprinkler Systems for Facility Managers, Part 7

Posted by Jason Hugo on 9/11/2018 to How a Fire Sprinkler Works
Air Compressor Sprinkler
A floor mounted air compressor. Photo courtesy of the National Fire Sprinkler Association 

NFPA inspections of automatic detection systems and air compressors

In this installment of QRFS’ series on the inspection of commercial automatic fire sprinkler systems, we detail the National Fire Protection Association (NFPA) requirements for the inspection of automatic fire detection equipment and air compressors. 

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Automatic detection equipment in pre-action and deluge fire sprinkler systems 

Automatic detection equipment in the specific context of sprinkler systems typically consists of heat or smoke detectors connected to a pre-action or deluge fire sprinkler system. Other automatic detectors will of course be present in a wider life safety system, and their inspection and installation requirements are covered in NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems and NFPA 72: National Fire Alarm and Signaling Code.

Before getting too deep into the inspection requirements for automatic detection equipment in these specific sprinkler systems, it may be helpful to brush up on what pre-action or deluge systems are by reviewing a previous QRFS blog post. Here’s how NFPA defines them and a key component:

From the 2016 Edition of NFPA 13 and 2017 Edition of NFPA 25

Preaction Sprinkler System. A sprinkler system employing automatic sprinklers that are attached to a piping system that contains air that might or might not be under pressure, with a supplemental detection system installed in the same areas as the sprinklers.

Deluge Sprinkler System. A sprinkler system employing open sprinklers or nozzles that are attached to a piping system connected to a water supply. This supply is accessed via a valve that is opened by the operation of a detection system installed in the same areas as the sprinklers or the nozzles. When this valve opens, water flows into the piping system and discharges from all sprinklers or nozzles.

Pilot Line Detector. A standard spray sprinkler or thermostatic fixed-temperature-release device used as a detector to pneumatically or hydraulically release the main valve, controlling the flow of water into a fire protection system.

Pilot Line Detector
A double-interlock pre-action system with a pilot line detector on the left and a pendent sprinkler on the right. Photo courtesy of the National Fire Sprinkler Association

Preaction Pilot Line
A double-interlock pre-action system with pilot line detectors. Note the galvanized pilot line that resembles sprinkler pipe. Photo courtesy of the National Fire Sprinkler Association

Pre-action and deluge fire sprinkler systems only send water when an electric, hydraulic, or pneumatic releasing device, or detection equipment, is activated by fire, smoke, or a pull station. An electric automatic detection system consists of fire, heat, or smoke detectors. The hydraulic or pneumatic detection systems are activated through pilot lines. Pilot lines can look almost like a redundant sprinkler system that runs parallel with sprinkler branch piping; however, a pilot system uses smaller and galvanized piping with sprinklers or other thermal responsive mechanical devices. 

Regardless of the method, the activation of a fire, heat, or smoke detector or pilot line detector initiates the action to fill the fire sprinkler system with water.

Thermal-style detectors are the most common and oldest type of automatic detection devices:

  • Most units are fixed-temperature devices that operate when the room reaches a predetermined temperature. A fixed-temperature, line-type detector consists of two cables and an insulated sheathing that is designed to break down when exposed to heat. The advantage of line-type over spot detection is that thermal sensing density can be increased at a lower cost.
  • The second-most-common type of thermal sensor is the rate-of-rise detector, which identifies an abnormally fast temperature climb over a short time period. These units are “spot type” detectors, which means that they are periodically spaced along a ceiling or high on a wall. 

The below video explains how a fixed-temperature heat detector works, as well as how it is wired to a fire alarm control panel:

Automatic detection equipment inspections

NFPA 25 details the inspection requirements for automatic detection equipment. As with all inspections, the purpose is to visually observe the condition of the installed equipment. 

From the 2017 Edition of NFPA 25

 13.9.1 Automatic detection equipment used to actuate water-based fire protection systems shall be inspected, tested, and maintained in accordance with NFPA 72.

 13.9.2 Automatic detection equipment used to actuate water-based fire protection systems that is not covered by NFPA 72 shall be inspected, tested, and maintained to ensure that the detectors are in place, securely fastened, and protected from corrosion, weather, and mechanical damage and to ensure that the communication wiring, control panels, or pneumatic tubing system is functional.

Smoke Detector Preaction System
A smoke detector for pre-action system. Photo Courtesy of the National Fire Sprinkler Association

It is important to note and differentiate the two above sections from NFPA 25. The first section (13.9.1) sends the user to NFPA 72: National Fire Alarm and Signaling Code, which covers automatic electric or electronic devices, such as heat and smoke detectors. The second section (13.9.2) applies to other automatic detection equipment such as pilot line detectors. 

Here is the relevant code from NFPA 72 on the former group:

From the 2016 Edition of NFPA 72

 14.2.1.3* The purpose for periodic inspections is to assure that obvious damages or changes that might affect the system operability are visually identified.

 14.3.1* Unless otherwise permitted by 14.3.2, visual inspections shall be performed in accordance with the schedules in Table 14.3.1 or more often if required by the authority having jurisdiction.

 14.3.2 Devices or equipment that is inaccessible for safety considerations (e.g., continuous process operations, energized electrical equipment, radiation, and excessive height) shall be permitted to be inspected during scheduled shutdowns if approved by the authority having jurisdiction.

Where facilities have the duty and responsibility to do inspections through NFPA 25, the same authority and responsibility is in NFPA 72. A visual inspection is made by observing the automatic detection equipment condition on a semi-annual frequency. Look for paint on equipment, such as smoke and heat detectors and pilot line detectors, missing equipment, physical damage, or excessive dirt and dust (aka “loading”).

Note that mild-to-moderate loading can be removed on some automatic detection devices without touching them with a SprinklerVac.

From the 2016 Edition of NFPA 72

NFPA Visual Inspections Detection Equipment
NFPA 72 stipulates that the visual inspection should be done twice per year.

Air compressor inspections

Air compressors can play a big part in fire protection systems, especially when it comes to dry pipe fire sprinkler systems. Dry pipe systems are installed in freezing environments and the air compressor pressurizes the sprinkler piping network to keep the water out it until a fire occurs. Air compressors are located near the dry pipe valve and are connected to it with an air maintenance device. NFPA 25 outlines the visual inspection requirements in Section 13.10:

From the 2017 Edition of NFPA 25

 13.10.2.1 Air compressors dedicated to water-based fire protection systems shall be inspected monthly to verify the following:

 (1) Air compressor is free of physical damage.

 (2) Power wiring to the air compressor is intact and free of physical damage.

 (3) Piping from the air compressor to the fire protection system is intact and free of physical damage.

 (4) The means of anchoring the air compressor to the structure or to the system piping is secure, tight, and free of physical damage.

 (5) Air compressors requiring oil have the required amount of oil in the oil reservoir.

Riser Mounted Air Compressor Sprinkler
A riser-mounted air compressor. Source: Fire Protection Deficiencies

As with all fire protection equipment, any type of physical damage could compromise the integrity and operation of the component. Therefore, NFPA 25 requires monthly inspections of air compressors, which are notorious for vibrating connections loose during continuous operation. Inspectors must check for the following:

  1. Verify the mounting brackets or anchoring provisions remain secure.

  2. Ensure wiring is intact, undamaged, and safe. 

  3. Check that the air supply from the air compressor to the air maintenance device is not damaged. 
Also verify that the air compressor is free of damage from any impact as well as corrosion. Oil-lubricated motors are becoming a thing of the past for new installations and construction, but plenty of existing air compressors with fillable lubrication remain. 

The inspection requirements from NFPA 25 do not cover all of the air compressor inspection duties. According to NFSA ITM Specialist Vince Powers, “It is important to follow the air compressor manufacturer requirements also. While facility managers are doing the monthly inspection, one of most missed items on minor air compressor maintenance is draining the condensation in the air tank. Allowing the condensation to build can impact air compressor operation, decrease service life, increase  tank corrosion which increases the potential of scale and debris to foul the air maintenance device and operation of the dry pipe valve.”

Air Maintenance Device Fire Sprinkler
An air-maintenance device. Photo courtesy of the National Fire Sprinkler Association

This concludes the NFPA inspection requirements for automatic detection equipment and air compressors


Be sure to check out our previous blogs in the series:







If you need to buy parts for your commercial fire sprinkler system, check out QRFS’ selection of commercial fire sprinkler heads, cover plates, escutcheons, and other components and tools, or just use the search bar at the top of the page to find what you’re looking for.
If you have any questions about commercial fire sprinklers or need help finding an item, give us a call at 888.361.6662, comment below, or fill out our contact form and we’d love to assist.

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