AquaMatic – 43725 – Cap, 5521, Lower, Noryl, Machined, Replaces part 1075348

The AqMatic 43725 is a lower cap for 5521-series diaphragm valve assemblies, manufactured from machined Noryl and designed as a direct replacement for part 1075348.

This component forms the lower housing section of the valve bonnet assembly, enclosing internal components such as the diaphragm, spring, and plates. In 5521 isolated bonnet valve designs, the lower cap is critical for maintaining structural integrity, sealing alignment, and proper internal pressure containment during operation.

Noryl construction provides corrosion resistance and dimensional stability, making it suitable for water treatment, filtration, and chemical systems where metal components may degrade over time.

Because this part is tied to a specific valve geometry, it must be matched exactly to 5521 configurations. It is typically replaced during rebuilds when cracking, wear, or thread damage compromises the integrity of the valve housing.

This component is commonly serviced alongside diaphragm kits, plates, and springs in systems that also include V42 diaphragm valves, K53 series valves, and control systems using stagers.