We’ve spent a lot of time recently focusing on Waukesha Positive Displacement Pumps, but in today’s post we wanted to pivot a take a look at Waukesha’s industry leading line of single seat valves– the W60 series. More specifically, we wanted to look at stem adapters, the options available, and when you should use them. We’ve been getting a lot of questions about this recently and hopefully this post is a resource to those folks.
To start, let’s take a look at the standard adapter and what an adapter really is. The adapter on a Waukesha W60 series valve is machined from 316LSS bar stock and provides strength to the valve body and also serves to align the stem. The outer perimeter of the adapter has an o-ring that seals the body from atmosphere and is forward in the body to minimize crevices to make the valve cleanable.
The valve stem then passes through the center of the adapter and is also sealed with an o-ring. A TFM split bearing or bushing then guides the stem and bears the mechanically loading imparted by hydraulic forces.
We use the standard adapter in probably 85-90% of applications. They are generally pressure rated close to the actuator holding pressure (especially at lower or ambient temperatures) and are designed to be easily cleaned. As a rule of thumb, with temperatures less than 160 F and valves 3” and smaller, we’ll be fine at 250 PSI.
High Pressure Adapter
The weak point in the W60 adapter is the sealing capability of the dynamic o-ring on the product stem. For high pressure applications, especially with hot fluids, we risk blowing product past that o-ring. In the high-pressure variation of the W60 adapter, we add a backing ring on the atmospheric side of the adapter to support the stem o-ring, as well as a bolted high-pressure clamp to support the adapters outer static o-ring. This boosts the pressure rating of the adapter considerably- up to 1,220 PSI on a 1” W60 series valve. The product stem still passes through the adapter and is guided by a TFM split bearing. Applications where we are using a high-pressure adapter are applications greater than 200 PSI or 200 F. Think reverse osmosis applications. And it’s important to remember this is just the pressure rating on the adapter- not the holding pressure of the valve.
W80 Aseptic Adapter
The W80 adapter is used to convert a W60 valve to a W80. The outer perimeter is still sealed to the valve body with a static forward o-ring to minimize crevices. But where the stem passes through the adapter, we add a second dynamic o-ring, so we seal in the upper and lower portions of the adapter and then also machine the adapter to allow for a flush between the two o-rings. Typically, we flush with a compatible liquid or steam.
Wiping Stem Seal
The final adapter option we have is the wiping stem seal. We are using this adapter for high-risk and hard to clean product applications. In this design, we have a two-piece adapter with a wiping seal located on the lower body in the product zone that acts like a squeegee, removing product from the product stem as it moves through the adapter. This adapter is great for thick, viscous products that can cake, solidify, or plate out on the stem or in the adapter. And the two-piece design allows for easy maintenance or replacement of the wiping stem seal.
In sum, we have four different adapter options for Waukesha single seat valves- standard, high pressure, aseptic, and wiping stem. Standard will work for most applications, but for high pressure, high temperature applications, we may opt for the high-pressure adapter. For aseptic or barrier applications, we’ll use the W80 adapter, and for thick products that plate and coat, we’ll use the two-piece wiping stem seal. We’ll continue come back to other features and considerations for applying Waukesha W60 single seat valves, but until then, if you have any questions about your sanitary valving application, contact a Triplex Sales Engineer today!