Apollo Trading Company: Service That Exceeds Expectations! Leading supplier of temperature and pressure instrumentation including diaphragm seals, tri-clamps, pressure syphons, needle valves, thermowells, snubbers, test kits, and Fluitek filtration elements. We also carry pressure gauges, thermometers, transmitters, switches and accessories used in the HVAC, petrochemical, dairy, food and beverage industries..