The Castair F-10D-025 is a complete intake air filter assembly for piston compressor pumps with a 1/4" NPT inlet port. It mounts directly on the pump head, filters incoming air through a paper element (the 10D element), and quiets the intake pulse that unprotected pump ports produce. If you have a Castair pump with a 1/4" intake port and the original filter is damaged, clogged beyond service, or missing entirely, this is the replacement assembly.
What This Filter Does
Piston compressors pull in ambient shop air on every intake stroke. In a working shop — concrete dust, metal particles, carbon deposits, general airborne grit — unfiltered intake air accelerates cylinder wall wear, scores valve seats, and shortens pump life significantly. The F-10D-025 installs on the pump intake port and uses a paper filter element (the 10D element) to capture particulates before they reach the compression chamber.
The assembly also acts as an intake silencer. The thumping intake noise on an unfiltered pump is loud and fatiguing. With the filter housing in place, that noise drops to a manageable level.
Key Specifications
- Part Number: F-10D-025
- Inlet Size: 1/4" NPT
- Outer Diameter: 3.25"
- Overall Height: 3.50"
- Flow Rating: 12 CFM
- Filter Element: 10D paper element (replace separately)
- Construction: Cast iron
F-10D Series — Available Configurations
The F-10D series covers three inlet sizes in the same compact housing (3.25" OD, 3.50" overall height, 12 CFM). All three use the same 10D replacement element:
- F-10D-025 — 1/4" NPT inlet
- F-10D-038 — 3/8" NPT inlet
- F-10D-050 — 1/2" NPT inlet
Match the inlet size to the threaded port on your pump head. For pumps in the 20-60 CFM range needing larger inlets (1/2" through 1-1/2"), Castair's S-16D and S-20DP silencer-filter series covers those applications.
When Does a Shop Need This
- Replacing a cracked, broken, or missing intake filter on a Castair pump with a 1/4" inlet
- The filter element seat is damaged and the element will not seal properly
- Rebuilding or remanufacturing a Castair pump and need the complete intake assembly
- Compressor is notably louder at intake than normal — a missing or deteriorated filter housing amplifies intake noise significantly
Note: The 1/4" NPT inlet size is on the smaller end of the Castair pump lineup. If you are not certain of your pump's inlet port size, measure the threaded port directly rather than guessing from tank size or motor HP.
Replacement Element
The F-10D-025 uses the Castair 10D paper filter element. Replacement interval depends on your shop environment — dusty conditions require more frequent service. A restricted intake element forces the pump to work harder and run hotter. Keep a spare 10D element on hand so you can swap it without downtime.
Why Buy From OEM Diagnostic Tools?
OEM Diagnostic Tools has supplied professional shop equipment and components since 2016. We stock Castair parts so shops can get what they need without tracking down distributors. Free shipping on qualifying orders, free tech support at 866-217-0063, and full manufacturer warranty on every part. If you need to confirm the correct inlet size for your pump before ordering, call us.
Call 866-217-0063 for quick answers and help!
