Johnson Controls A-4000-120 Oil Indicator

The Johnson Controls A-4000-120 is a precision oil indicator with needle valve assembly designed for critical diagnostics in pneumatic control systems. Engineered to detect aerosol-mist levels of oil entrainment, this instrument ensures that compressed air remains within the strict purity standards required to prevent fouling of downstream pressure reducing valves and sensitive pneumatic components. With a high level of sensitivity, the device can measure oil concentrations as low as 0.01 PPM (0.012 mg/m?) by utilizing a color-change cartridge and a calibrated conversion chart.

This HVAC pneumatic air indicator operates within a line pressure range of 10 to 125 PSIG (70 to 875 kPa). Technicians typically install the A-4000-120 at the compressor tank discharge or between the filtration stage and the main supply line. The integrated needle valve allows for controlled flow (less than 0.2 SCIM/PSIG) through the plastic indicator tube, where a red oil-soluble dye tracks through white reagent material to provide a quantifiable visual reading of system contamination. Its 1/8 inch NPT brass construction ensures durability and leak-free performance in professional mechanical equipment rooms.

Key Benefits

• Precision Detection: Accurately measures oil aerosols down to 0.01 PPM to prevent system-wide contamination.
• High Sensitivity: Optimized for compressed air systems, allowing for early detection of compressor oil carryover.
• Versatile Compatibility: Designed for standard 1/8 inch NPT fittings used in Johnson Controls A-4000 series filter and reducing stations.
• Easy Diagnostics: Includes a conversion chart for fast, field-level analysis of oil concentration without laboratory equipment.
• Reliable Monitoring: Supports scheduled maintenance cycles by verifying the efficiency of coalescing and activated charcoal filters.

Common Questions

Where should the indicator be installed for the most accurate reading?
For monitoring compressor performance, install the unit at the tank discharge. To verify filtration efficiency, install it between the oil filter and the pressure reducing valve (PRV) where the air is driest.

Can I reuse the indicator cartridge after a test?
No. Once the red dye has migrated up the tube, the cartridge is spent. The needle valve should be closed, and the old cartridge replaced with a new A-4000-121 element for the next diagnostic check.

What is the maximum pressure limit for this valve assembly?
The A-4000-120 is rated for a maximum line pressure of 125 PSIG. Exceeding this pressure or loosening the retaining nut while pressurized can cause the indicator tube to disconnect.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.