Diaphragm Valve Manual Bonnet Selection

Since 1997, Steel & O'Brien manual bonnet assemblies have delivered proven performance in demanding sanitary processing applications. Built on a time-tested design, these assemblies combine durability, reliability, and user-friendly operation with premium standard features that are often considered optional upgrades on competitive models. Standard features include:

• Sanitary internals
• FDA FKM O-ring sealed hand wheel and stem
• The non-galling internal stem assembly
• Stainless steel bonnet body with an electropolished exterior
• Fully autoclavable

Depending on the process and end-user requirements, there’s probably a Steel & O'Brien bonnet assembly that will meet your need.

Standard Open/Close applications

If the adjustability of either the compression or the limiting of the open position of the diaphragm is not of concern, a non-adjustable type bonnet is the best and most economical option.

#12 bonnet

• Stainless steel base with PPS thermoplastic hand wheel (valve sizes ½” – 2”).
• PPS thermoplastic is very chemical and temperature resistant thermoplastic and can easily withstand wash down, autoclave and sterilizing chemical wipe down protocols.
• The stainless steel base is electropolished for both increased chemical resistance and for aesthetic purposes.

#60 bonnet

• Stainless steel base with stainless steel hand wheel (valve sizes ½” – 2”).
• The #60 bonnet assembly is essentially the same bonnet as the #12 bonnet, but with an electropolished hand wheel.
• If diaphragm changes are regularly made after valve assembly installation, many times the PPS hand wheel can be broken due to the assembly being dropped. The stainless steel hand wheel version is typically selected to prevent breakage and/or increased chemical resistance.

#9 bonnet

• Stainless steel base with stainless steel hand wheel (valve sizes 2-1/2” – 4”).
• The #09 bonnet is a Steel & O'Brien standard bonnet assembly for valve sizes over 2” and incorporates the same features and benefits as the #60 bonnet.

18A bonnet

• Stainless steel base with PPS thermoplastic hand wheel (Compact valve sizes ¼” – ½”).
• The #18A bonnet is a Steel & O'Brien standard bonnet for BioFlo II series compact/lab size valves and incorporates an ergonomically designed hand wheel. The adjustable close stop can be set with a simple turn of a set screw within the bonnet assembly without any disassembly, thus preventing the possibility of losing any small parts during bonnet adjustment.

#15 bonnet

• Stainless steel base with PPS thermoplastic hand wheel and gradient position indicator (valve sizes ½” – 2”).
• Steel & O'Brien #15 open stop bonnet assembly gives the user the flexibility to set the desired open position, lock it into place to allow the valve to be opened to the same position every time, and the ability to see relative valve position via the gradient indicator incorporated into the bonnet.