Kromschroder Safety diaphragm (Compensating / Safety Diaphragm) VGBF/VAR 65 /B 74924640

This is a safety (compensating) diaphragm for Kromschroder VGBF/VAR 65 /B gas pressure and differential pressure regulators. It is made of perbunan (NBR) rubber, resistant to natural gas and liquefied gas (propane-butane). The diaphragm senses inlet pressure changes and counteracts them to maintain stable output pressure. It is a genuine spare part, SKU 74924640, with a nominal diameter of 65 mm, manufactured in Germany, and covered by a 1-year warranty. It fits Kromschroder VGBF 65 /B regulators.

Parts of this type are selected by matching the exact valve series and size, as indicated on the valve body marking (e.g., VGBF/VAR 65). Before ordering, verify the valve model and connection size, and ensure the diaphragm is compatible with the specific regulator type (pressure or differential pressure). Installation requires inspecting the valve body and sealing surfaces for deposits or damage, and checking the valve seat and coil condition. The diaphragm is not interchangeable between different valve families or brands, so it must be sourced as a genuine part for the specific valve.

Over time, diaphragms of this kind can stiffen, crack, or lose their shape, causing the valve to fail to open, close slowly, or leak gas. This may result in unstable outlet pressure, combustion instability, or failure to maintain the correct pressure difference. If the diaphragm is part of a servo regulator, its failure can cause erratic pressure control. Check the diaphragm for wear, damage, or deformation, and inspect the valve seat and sealing surfaces for issues.