Perfect for waste drains and low-pressure aquaculture Knife gate valves are economical, quick-acting valves for clean and dirty water low-pressure applications. They have become very popular in the aquaculture industry for several reasons: they can be easily taken apart, the seals can be changed and even the valve body can be changed without upsetting the ends that may be glued to your pipes. Therefore, they can be used in place of unions! If you have a valve glued in place, but want to take it out, you can simply unbolt it and purchase new side pieces. They offer unrestricted flow and are quick opening, 100% water tested at the factory and quite low in cost. These 11/2” to 8” valves are all PVC with stainless steel shafts, polypropylene knife gates (except for 4”, 6” and 8”, which are stainless steel), and have TPE seals. The valves listed are all slip x slip, they are not for use in freezing weather. One-year warranty.