Dry Air Series Compressor Guide
Dry Air Series Air Compressors are FM Approved systems specifically designed for dry pipe and pre-action sprinkler systems in freezer/refrigerated rooms and cold storage areas. The regenerative drying process (four molecular sieve towers) dries system air to a less than -40°F (-40°C) dewpoint, preventing the dangerous formation of ice plugs in cold storage systems and stopping the corrosion process.
NFPA 13 8.8 - Refrigerated Spaces
In spaces maintained at temperatures below 32°F (0°C), air or nitrogen supply for systems shall be one of the following:
- Air from the room of the lowest temperature to reduce the moisture content
- Air compressor/dryer package listed for the application utilizing ambient air
- Compressed nitrogen gas from cylinders used in lieu of compressed air
Problems
- Drawing air from the lowest temperature room does not guarantee moisture-free air and adds more steps to the installation process.
- Competitor FM Approved dry air solutions require long, complex startup procedures and are expensive and time-consuming to maintain.
- Nitrogen systems do not provide the same level of control and efficiency in achieving low dew points as regenerative drying systems.
Solution
To effectively dry air, it must be passed through desiccant at high pressure. The FM Approved R900 and R1700 models are designed with a two-stage pump and three stages of drying. A cracking pressure check valve ensures steady high-pressure airflow, which first passes through an oversized aftercooler. It then moves through an oil coalescing filter, automatic water separator, and two stages of regenerative Type 4A molecular sieve canisters. This regenerative drying system achieves a -40°F (-40°C) dew point within minutes, eliminating the need for complex 8-hour start-up procedures.
The spin-on canisters are easy to change and only require replacement every three years, which greatly simplifies maintenance requirements and reduces the cost of ownership.
A Programmable Logic Controller (PLC) is programmed to cycle each canister between absorptive and regenerative modes and finish the regenerative process once the compressor stops running. The extra dry air is stored in a 60-gallon tank.
Molecular Sieve
Efficient
The Type 4A molecular sieve is smaller than both silica gel and activated alumina, which means the same amount has more surface area and drying power. Type 4A also lasts longer.
Low Maintenance
A replacement is needed every 3 years, compared to every year for activated alumina.
Frustration-Free Desiccant Change
“Spin-on” canisters are easy to replace and do not require manual removal of activated alumina, which is prone to clumping, from desiccant tanks.
Clean
It doesn’t generate contaminants under pressure, leading to dust-free downstream air.
Innovative Technology
Our research indicates that three stages of drying at higher pressure are the most effective way to reach -40°F (-40°C) dew points in hot, humid environments. A low RPM, two-stage compressor fills the tank to high pressure before cracking the pressure check valve allowing air to flow downstream. As the system fills, pressure increases, which improves the efficiency of the drying process. An advanced PLC compressor controller and zero-loss tank drain minimize runtime and energy waste. A coalescing filter and oil water separator provide trouble-free flow without moisture and oil vapors. The coalescing pre-filter is anodized outside and inside, which makes it less likely to plug or foul. Inferior industry-standard filters are based on 50-year-old cast designs, not specifically designed for fire suppression, and are notorious for failing.
Stage 1
A large aftercooler, or heat exchanger, removes up to 80% of moisture and reduces dew point to 10 to 15°F (-12 to -9°C) above ambient temperature. A uniquely designed automatic water separator removes all condensate.
Stage 2
The first set of regenerative Type 4A Molecular Sieve canisters reduces dew point to less than -40°F (-40°C) in a 74°F (23°C) environment. We use oversized coalescing filters to protect the desiccant from harmful oil vapors.
Stage 3
The second set of regenerative canisters reduces the dewpoint to less than -80°F (-62°C) in a 74°F (23°C) environment, or to less than -40°F (-40°C) dew point in a 100°F (38°C) and 90% RH environment.
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