For a new aftercooler or separator we need the compressor's delivery in SCFM and its discharge pressure and temperature, the cooling water or ambient air temperature, and the outlet temperature the plant needs. For an oil or closed-circuit cooler, the heat load or the flow and temperature drop, the fluid, and what is available to cool against.
If you are replacing an existing unit, the IPAC or HiROSS model number from the nameplate is usually all we need - W0110FA000, S4AHA0, SAC120, STA05024 and the like tell us the size, the pressure class and the options. If the plate is gone, measure the shell diameter, the overall length and the connection sizes and positions, and photograph the unit.
Every part number on this site has its own page: start at All Part Numbers, or decode the number with the Model Number Guide. Call or email and we will confirm the match before anything is quoted.