MDI Mercury Displacement 235NO 24A 18 Contactor R 22 Key Benefits: Dual Function Design: Functions Key Benefits: Dual Function Design: Functions as a liquid receiver to store refrigerant during varying load conditions and a muffler to suppress compressor discharge noise The Watts 0346040 (Series 174A) is a high capacity ASME Section IV boiler pressure relief valve designed for commercial and industrial hot water heating applications this low maintenance HVAC contactor is built for millions of cycles in demanding environments Deviating from a vertical orientation will cause the contacts to fail to close or open correctly