Castair Refrigerated Air Dryer — 161 CFM @ 37F (RD166-37K)
The Castair RD166-37K is a large-capacity refrigerated compressed air dryer, rated for 161 CFM at a 37 degree F dew point (181 CFM at 50 degrees F). It connects with 1-1/2" NPT fittings, runs on 115V single-phase drawing 11.4 amps, weighs 137 lbs, and measures 11.4 x 33.7 x 24.5 inches. This is the largest standard-stocked model in the Castair refrigerated dryer lineup and is sized for higher-output compressors in the 25-40 HP range producing up to 130 CFM at standard conditions.
Note: The Castair catalog lists the comparable model as the RD161-37K (161 CFM at 37F). If your system requires exactly 166 CFM or above, contact us at 866-217-0063 — Castair makes custom larger sizes available by phone quote for flows above the standard lineup.
Performance Specifications
- Model: RD166-37K
- CFM capacity @ 37 degree F dew point: 161 CFM (per published Castair data for this size class)
- CFM capacity @ 50 degree F dew point: 181 CFM
- Rated at: 100 degree F inlet air, 100 degree F ambient, 100 PSI
- High-temp derating: At 150 degree F inlet, capacity reduces to approximately 55% (approx. 89 CFM)
- Target dew point: 37 degrees F
- Maximum inlet pressure: 232 PSIG
Physical and Electrical Specifications
- Inlet/outlet connections: 1-1/2" NPT
- Voltage: 115V, 1-phase, 60 Hz
- Power cord: 9-foot, 3-prong
- Current draw: 11.4 amps
- Weight: 137 lbs
- Dimensions (WxDxH): 11.4" x 33.7" x 24.5"
- Refrigerant: R134a and R407c
- Quick-connect refrigerant recharge port: Yes
- UL listed: Yes
Key Design Features
- Heat exchanger: Stainless steel, dual-function single-body
- Condensate drain: Automatic, demand-activated — only cycles when water is present
- Dew point indicator: Visual — no computer programming required
- No computer logic: Simple to operate and troubleshoot
- 1-1/2" NPT connections: Match your main air header line — keep resistance low on high-flow systems
Castair Refrigerated Dryer Lineup
| Model | CFM @ 37F | Connections | Amps | Weight |
|---|---|---|---|---|
| RD25-6K | 25 | 3/4" NPT | 3.0 | 57 lbs |
| RD59-11K | 59 | 3/4" NPT | 6.5 | 73 lbs |
| RD71-15K | 71 | 1" NPT | 7.5 | 110 lbs |
| RD113-60K | 107 | 1" NPT | 9.0 | 119 lbs |
| RD166-37K | ~161 | 1-1/2" NPT | 11.4 | 137 lbs |
For systems requiring more than 161 CFM, call Castair directly or contact us at 866-217-0063 — larger dryers are available by quote.
When Does a Shop Need This Dryer?
The RD166-37K is sized for: 25 to 40 HP rotary screw compressors producing up to 160 CFM. If you have a 30 HP R30312 unit producing 130 CFM, or a multi-compressor bank totaling that flow, this is the dryer that handles the full output without derating the system.
Critical sizing note: Ratings are based on 100 degree F inlet air and 100 degree F ambient temperature at 100 PSI. Compressor rooms that run hotter than 100F require you to apply the 55% derating factor. A dryer that is technically rated for your flow at 100F inlet may be undersized at 120F or 130F inlet. If your equipment room runs hot, size up.
Pre-filter is required for warranty: Install a properly sized particulate pre-filter (Castair C-FS or equivalent) upstream of this dryer. The 1-1/2" NPT inlet means you need at least a FS112 or FS114 filter on the incoming line — call 866-217-0063 for pre-filter recommendations.
Installation Options
- Inline installation between compressor discharge and air header
- For this size dryer (1-1/2" NPT), Castair recommends the DP100 installation option — bypass valve plumbed but dryer not mounted directly on compressor
- Use a Castair metal flex hose and bypass valve to allow dryer maintenance without shutting down the air system
What Is in the Box
- Castair RD166-37K refrigerated air dryer
- 9-foot, 3-prong power cord
- Automatic condensate drain
- Dew point indicator
Pre-filter is required (not included) — contact 866-217-0063 for pre-filter sizing.
Why Buy From Air Compressor Factory Direct?
- Castair specialists: Full dryer lineup plus filters, pre-filters, bypass valves, and flex hose
- Free shipping to commercial addresses
- Free tech support: 866-217-0063 — dryer sizing, pre-filter selection, installation configuration
- Honest guidance: If your system needs more than 161 CFM, we will tell you upfront and get you a quote on larger capacity
Call 866-217-0063 for quick answers and help!
