The Castair 16DP is a replacement air filter element for the S-16D-100 assembly used on C1, C2, and C3U pumps. This filter element fits the 1" inlet silencer/filter housing and is designed for Castair's larger industrial two-stage compressor pumps. At $10.01, this is a maintenance item — one you should have on hand before you need it, because a clogged or missing intake filter kills pump efficiency and shortens pump life. The 16DP element has a foam pre-filter in addition to the main element, which is the distinction from the standard 16D element.
Filter Element Specifications
- Part Number: 16DP
- Fits Assembly: S-16D-100 (1" inlet silencer/filter assembly)
- Compatible Pumps: C1, C2, C3U (and VA80 per filter chart)
- Inner Diameter: 3 inches
- Outer Diameter: 4-3/8 inches
- Height: 2-1/8 inches
- Pre-filter: Yes — foam pre-filter included
- Price: $10.01 per element
Which Filter Do You Need: 16D vs. 16DP?
Both the 16D and 16DP share the same physical dimensions — 3" ID, 4-3/8" OD, 2-1/8" height. The difference is which assembly they go into and which pumps they serve:
- 16D ($7.70): Fits the S-16D-075 assembly (3/4" inlet). Used on A4 and A8 pumps (smaller single-stage pumps, 3.5-5 HP range)
- 16DP ($10.01): Fits the S-16D-100 assembly (1" inlet). Used on C1, C2, C3U pumps — the larger two-stage pumps used in 4-15 HP industrial compressors. Also comes with the foam pre-filter for additional particulate protection
If you are not sure which pump you have, look at the pump casting or your original compressor spec sheet. C1 pumps are 4-7.5 HP, C2 pumps are 7.5-10 HP, and C3U pumps are used in some 15 HP configurations. All three use the 16DP element.
The Foam Pre-Filter
The 16DP, 20DP, and 32DP filter elements all include a foam pre-filter. The foam layer catches larger particles before they reach the main paper element, extending service life between changes. In a dusty shop environment, the foam pre-filter can be inspected and cleaned separately during regular maintenance without replacing the entire element.
Why Intake Filtration Matters
The intake air filter does two jobs: it removes particulates from the air entering the pump cylinders, and the silencer housing attenuates intake noise. A clogged filter restricts airflow, which means the pump works harder to move the same volume of air — higher temperatures, more wear, and lower output. On a cast iron industrial pump like the C1 or C2, replacement pump costs run into the hundreds or thousands of dollars. A $10 filter element is cheap insurance.
Replacement Interval
Castair does not publish a specific interval — it depends on the air quality in your shop. Inspect the element every oil change (every 1,000 hours or annually). In a dirty environment (welding shop, woodworking, dusty concrete floors), inspect monthly. Replace when the element is visibly dirty or when you notice decreased output pressure.
What's in the Box
- 1x Castair 16DP replacement filter element with foam pre-filter
Note: Filter housing (S-16D-100 assembly) sold separately. The element slips into the existing housing — no tools required for element replacement in most applications.
Compatible Right From The Start Kits
Castair's RFS001 and RFS002 start-up kits include two 16D elements per kit (two filters, one per pump side or two for duplex). The 16DP is the element for the 1" inlet assembly — if your Right From The Start kit called for 16D but you have a C1/C2/C3U pump, verify with your pump model which element is correct. Call us at 866-217-0063 if you are unsure.
Why Buy From Air Compressor Factory Direct?
We have been specializing in industrial air compressor components since 2016. We stock Castair replacement parts including filter elements, oil, belts, and hardware — the maintenance items that keep your system running. Free shipping on all orders, free technical support at 866-217-0063, and full manufacturer warranty on all Castair parts.
Call 866-217-0063 for quick answers and help!
