All Kynar pumps which had been constructed using Carbon Filled Kynar are being switch to Glass Filled Kynar. The Carbon Filled Kynar is black in color. The Glass Filled Kynar is yellow. The most important reason for this change is the Glass Filled Kynar has a higher resistance to Sodium Hypochlorite then the Carbon Filled. The manufacturer of Kynar, Arkema, has tested the plastic with 20% Sodium Hypochlorite at 194F for 30 days and found no damage to the plastic. March has conducted its own testing, testing the parts at 14% Sodium Hypochlorite for the last 2 months at ambient, and no damage has been detected. March has also conducted pressure and temperature testing, and the Glass Filled Kynar meets or exceeds the Carbon Filled Kynar it is replacing. The Glass Filled Kynar also has the following certifications, FDA Food Compliant, 3A, USP Class VI, V-0, and NSF 61 

When repairing or replacing, the front and rear housings must be the same material as each other. Do not mix and match the housings. The impeller, of either material, will fit in both the Glass Filled Kynar and Carbon Filled Kynar housings. Instead of changing part numbers for the new material, the part numbers for the Carbon Filled Kynar parts now call for Glass Filled Kynar. If it is necessary for you to have Carbon Filled Kynar.