{"product_id":"pentair-union-diamond-seal-178746z","title":"Pentair Union Diamond Seal | Clean \u0026 Clear RP, Posi-Clear RP \u0026 Separation Tank | 178746Z","description":"\u003cp\u003eThe Pentair Union Diamond Seal (178746Z) is the OEM replacement seal for the union connections on Pentair Clean \u0026amp; Clear RP, Posi-Clear RP, System:2 Modular Media Filter, and Separation Tank filtration systems.\u003c\/p\u003e\n\n\u003cp\u003eThis seal maintains a watertight connection at the union joint on the filter body. A worn or damaged diamond seal allows water to weep or leak from the union, compromising system pressure and wasting water. Replacing this seal with the correct OEM part restores a secure, leak-free union connection.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; margin: 20px 0; border: 1px solid #ccc;\"\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003ePentair Part Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e178746Z\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003ePart Name\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eUnion Diamond Seal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003ePart Category\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSeals\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eQuantity Included\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e1 (Each)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eFits Into\u003c\/h3\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; margin: 20px 0; border: 1px solid #ccc;\"\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eBrand\u003c\/strong\u003e\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eEquipment Line\u003c\/strong\u003e\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eModel \/ Part Number\u003c\/strong\u003e\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eNotes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eClean \u0026amp; Clear RP\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eCLEAN \u0026amp; CLEAR RP\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e—\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePosi-Clear RP\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePXC100\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits all Posi-Clear RP filter models\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePosi-Clear RP\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePXC150\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits all Posi-Clear RP filter models\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePosi-Clear RP\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePXC200\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits all Posi-Clear RP filter models\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSystem:2 Modular Media Filter\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePLM100\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e—\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSystem:2 Modular Media Filter\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePLM150\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e—\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSeparation Tank\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSEP 48\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits Separation Tank SEP 48\/72\/96\/144\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSeparation Tank\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSEP 72\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits Separation Tank SEP 48\/72\/96\/144\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #ffffff;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSeparation Tank\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSEP 96\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits Separation Tank SEP 48\/72\/96\/144\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePentair\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSeparation Tank\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSEP 144\u003c\/td\u003e\n  \u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eFits Separation Tank SEP 48\/72\/96\/144\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cem\u003eCompatibility is based on Pentair parts documentation and available OEM records. This is not an exhaustive list. For certainty, verify the part number in your equipment's manual or on the original part itself before ordering.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003ePoolaroo Pro Tip\u003c\/h3\u003e\n\u003cp\u003eThe diamond seal profile on this part is designed specifically for Pentair's union joint geometry — do not substitute a generic flat gasket. When replacing this seal, clean the union face and seat thoroughly before seating the new part. Inspect the union threads and collar for cracking or distortion at the same time; a damaged union body will prevent the new seal from holding pressure regardless of seal condition.\u003c\/p\u003e\n\n\u003c!-- wft:processed:manual:2026-04-30 --\u003e","brand":"Pentair","offers":[{"title":"Default Title","offer_id":51774211129619,"sku":"178746Z","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0920\/0687\/5411\/files\/PEN178746Z_0.jpg?v=1747704305","url":"https:\/\/poolaroo.com\/products\/pentair-union-diamond-seal-178746z","provider":"Poolaroo","version":"1.0","type":"link"}