Castair Air Filter Element — Part# 8D (Fits A-Series and PK-Series Pumps)
The Castair 8D is the replacement air filter element for Castair A-series and PK-series compressor pumps. If your compressor is pulling in dirty air — dust, grit, shop debris — that contaminant goes through your valves, rings, and cylinders. A fresh filter element is not a luxury item. It is one of the cheapest forms of pump maintenance you can do, and it is the right thing to replace on a schedule rather than waiting until the element is visibly clogged or your pump starts running hot.
This element fits the 2140019A complete air filter assembly, which is the standard 1/2 in inlet filter used on the A-series and PK-series Castair pumps. If you are running a DD20, PK20, PK50, PK60, or PK65 pump, this is the correct replacement element. Keep a spare on the shelf — when you are doing a pump service, replacing the filter element at the same time adds about two minutes to the job and costs next to nothing relative to what contamination damage costs.
Filter Element Specifications
- Part Number: 8D
- Inner Diameter (ID): 1-1/8 in
- Outer Diameter (OD): 2-1/2 in
- Height: 1-7/8 in
- Inlet Size: Fits 1/2 in inlet (complete assembly is part# 2140019A)
Compatible Pumps and Assemblies
- 2140019A: Complete air filter assembly for 1/2 in inlet — the 8D element fits inside this housing
- DD20: Direct-drive pump
- PK20: PK-series pump
- PK50: PK-series pump
- PK60: PK-series pump
- PK65: PK-series pump
If you are not sure whether this element fits your specific pump, check the filter housing on your unit. The housing inlet size and the element dimensions (ID 1-1/8 in, OD 2-1/2 in, HGT 1-7/8 in) need to match. Call us with your pump model number and we will confirm compatibility before you order.
Why Air Filtration Matters on Cast Iron Pumps
Castair pumps are cast iron, oil-lubricated, and designed for a long service life. The design investment in cast iron and oil lubrication pays off when the pump is maintained properly. Air filtration is part of that maintenance. Your compressor pump is essentially an air pump — everything in the intake air passes through the filter before it reaches the valves and cylinders. Dust and particulate contamination accelerates valve wear, scores cylinder walls, and contaminates the oil. A clogged filter restricts airflow, makes the pump work harder, runs hotter, and delivers less CFM than it should.
Replacement intervals depend on your environment. A clean shop may go a full season without needing a new element. A dusty shop — grinding, woodworking, sandblasting nearby — may need element replacement every few months. The element is inexpensive enough that erring on the side of more frequent replacement is the right call.
Replacing the Element
The 8D element installs in the 2140019A filter housing. The process is straightforward:
- Relieve system pressure before working on the air intake — standard safety practice
- Remove the filter housing cover or cap from the pump inlet
- Pull out the old element — note its orientation if the housing has a specific orientation requirement
- Inspect the housing for cracks, damage, or contamination buildup — clean if needed
- Install the new 8D element and reassemble
- Confirm the housing is secure before returning the pump to service
Keeping Spare Elements on Hand
Ordering a single element is fine, but most shops doing regular maintenance order two or three at a time. The cost is low, the part is small, and having a replacement on the shelf means you do not skip the maintenance step because you have to wait for shipping. If you are servicing multiple Castair pumps on the same platform, ordering in small quantities makes sense.
Why Buy From Air Compressor Factory Direct?
- Castair parts specialists: We stock the correct OEM elements and can confirm compatibility with your specific pump before you order
- Free technical support: Call us with your pump model number and we will make sure you are ordering the right part
- Full manufacturer warranty: Genuine Castair parts, not aftermarket substitutes
- Fast shipping: Small parts ship quickly — you should not be waiting weeks for a filter element
- Full parts inventory: We carry the complete air filter assembly (2140019A) if you need the entire housing, not just the element
Call 866-217-0063 for quick answers and help!
