The Cast Air BG2-M is a 2-way pilot valve designed for gas engine-driven air compressors. It shares the same 1/4" NPT-F inlet, 20 CFM flow capacity, and direct vent with felt filter as the electric-application BE2-M, but is configured and rated for gas engine compressor control circuits. If you are running a portable gas-engine compressor — the kind that lives on a trailer or job site rather than a compressor room — and need to replace or upgrade the pilot valve that controls loading and unloading, this is the correct part.
At $78.54, it is the most affordable valve in the Cast Air pilot valve lineup. The lower price versus the BE2-M reflects the application differences, not a difference in build quality — both use the same hex brass body and corrosion-resistant construction.
What the BG2-M Does
- Application: Gas engine-driven air compressors — manages the pilot signal that tells the compressor to load or unload based on system pressure
- Valve Type: 2-way pilot valve — straightforward two-port design, one function per signal pulse
- Inlet: 1/4" NPT-F — matches standard pilot circuit ports on most gas engine compressor manifolds
- Vent: Direct vent with integral felt filter — exhausts signal pressure through a filter element rather than a piped exhaust line; keeps dirt out, keeps the vent clean
- Flow Capacity: 20 max CFM — right-sized for 1/4" pilot circuits; does not overpower small control lines
- Pilot Ports: 1/8" female NPT — standard connection for pilot signal lines
Construction and Adjustment
- Body: Hex brass — durable, corrosion-resistant, easy to thread without cross-threading or galling; hex flats make installation and removal straightforward with a standard wrench
- Pressure Adjustment: Full external adjustment — set the actuation pressure without opening the valve or pulling it from the compressor
- Differential Adjustment: Full external differential adjustment — controls the spread between cut-in and cut-out; important for gas engine applications where short-cycling can cause engine damage over time
- Pressure Range: 40–250 PSI available; most portable gas engine compressor applications use the 100–120 PSI range, though 140–170 PSI is available for higher-pressure systems — specify at order
- Corrosion Resistance: Corrosion-resistant construction — holds up on job sites, in trailers, and in environments where humidity and temperature swings are part of daily operation
Where This Valve Fits
- Direct replacement for failed or leaking pilot valves on gas engine compressors
- New builds where a reliable, adjustable pilot valve is needed for a 1/4" NPT gas engine control circuit
- Service situations where the original valve is hunting between cut-in and cut-out, or failing to hold signal pressure — adjust the differential after installation to dial it in
- Not for electric compressor applications — use the BE2-M for electric dual applications
- Not for high-flow 1/2" circuits — the BLG handles 60 CFM gas engine applications at 1/2" NPT
BG2-M vs. the Cast Air Pilot Valve Lineup
- BG2-M (this valve) — $78.54: 1/4" NPT-F, 20 CFM, gas engine, direct vent with felt filter — most affordable in the lineup
- BE2-M — $91.63: Same 1/4" NPT-F, 20 CFM, direct vent — electric dual application version
- BLG — $147.84: Steps up to 1/2" NPT-F inlet and outlet, 60 CFM — for larger gas engine compressor circuits
- BLE — $123.20: 1/2" NPT-F, 60 CFM, electric dual version of the BLG
If your gas engine compressor has a 1/4" NPT pilot circuit and draws 20 CFM or less through the control line, the BG2-M fits. If you are not sure about flow requirements, check the port size at the compressor — 1/4" NPT ports confirm this is the right valve. Need the gas engine version at higher flow? Step up to the BLG.
Technical Specifications
- SKU / Part Number: BG2-M
- Manufacturer: Cast Air (Castair)
- Valve Type: 2-Way Pilot Valve
- Application: Gas Engine
- Inlet Port: 1/4" NPT-F
- Outlet / Vent: Direct vent with felt filter
- Pilot Ports: 1/8" NPT-F
- Maximum Flow: 20 CFM
- Pressure Range: 40–250 PSI (specify range at order)
- Common Range Orders: 100–120 PSI or 140–170 PSI
- Body Material: Hex brass
- Adjustment: External pressure and differential adjustment
- Price: $78.54
Why Buy From Air Compressor Factory Direct?
- Specialist since 2016 — compressor components are our focus, not a side category; we stock what gas engine compressor operators actually need
- Free shipping on orders to the contiguous US
- Free tech support at 866-217-0063 — call us if you are not certain the BG2-M fits your compressor before you order
- Full manufacturer warranty — Cast Air backs their parts; we handle warranty issues directly
- Honest product matching — we will tell you if a different valve in the lineup is a better fit for your specific setup
Call 866-217-0063 for quick answers and help!
