The Castair RDD40SK is an accessory or service kit for the RDD40 refrigerated compressed air dryer. Based on the SK suffix in the part number, this is a solenoid kit or service kit — a component-level replacement part for maintaining the RDD40 dryer's automatic drain or control function. Castair accessories and service kits for the RDD40 series are designed to keep the dryer running without replacing the entire unit when individual components fail or wear out.
If you are troubleshooting an RDD40 that is not draining properly, draining continuously, or showing solenoid fault indications, this kit is likely what you need. Have your unit's symptoms and model variant ready when you call — we can confirm whether RDD40SK is the correct part for your specific failure mode.
Typical Applications
- Drain solenoid replacement: The automatic demand drain on Castair refrigerated dryers uses a solenoid valve to open and close the drain port. When the solenoid fails, the drain either sticks open (continuous air bleed) or sticks closed (moisture passes through the dryer untreated).
- Scheduled service: Solenoid valves have a finite cycle life. High-cycle environments — dryers on compressors that cycle frequently due to high air demand — wear solenoids faster.
- Component-level repair: Replacing the solenoid kit rather than the full drain assembly reduces repair cost and downtime significantly.
What's in the Box
- Castair RDD40SK service/solenoid kit for RDD40 refrigerated dryer
Note: Exact kit contents depend on the specific revision of this part number. Contact us at 866-217-0063 to confirm full contents and compatibility with your RDD40 model before ordering.
Compatible Equipment
- Castair RDD40 series refrigerated compressed air dryers (RDD40.016, RDD40.030, RDD40.060, and variants)
- Confirm compatibility with your specific dryer model and serial number before ordering
Technical Specifications
- Part Number: RDD40SK
- Manufacturer: Castair (Cast Air, Inc.)
- Application: Castair RDD40 refrigerated compressed air dryer
- Component type: Dryer accessory / service kit
Full electrical specifications (voltage, coil rating) and dimensions available by contacting us. Manufacturer specifications for this accessory are not published online — call for details.
Why Buy From Air Compressor Factory Direct?
We carry Castair service parts and can help identify the correct component for your RDD40 failure mode before you order. Free shipping on qualifying orders, free pre-sale technical support, and genuine Castair parts. If you are unsure whether RDD40SK is the right kit, call us — we will confirm before you place the order.
Call 866-217-0063 for quick answers and help!
