Sizing Spring Seals
Finding a replacement seal for your existing single spring seal is not as difficult as you may think. The key is getting one that fits onto your shaft and into your pump. To accomplish that your going to need to know some critical dimensions:
Single Spring Seals
More than anything you need to know what and how to measure up for seal replacement.
- Shaft Size (or sleeve size) of your pump
- Seal Head O.D.
- Working Length of Rotating portion of the Seal
- O.D. of the Stationary (or the bore dimension where the stationary press fits into).
- Thickness of the Seat.
Measure the Seal Head I.D. Add approximately .016″ to account for the squeeze the bellows must have to seal the shaft.
Measure the Rotating Units “Free Length”
Measure the Spring “Free Length”
Measure the seal head O.D. to be sure the seal will fit inside the stuffing box bore of the pump.
Determine the “Working length” of the seal.
Spring “Free Length” / 2 = Spring compressed length
Rotating Units “Free Length” – Spring compressed length = Rotating Units “Working Length”.
Because the seal your measuring may be used, or from another manufacturer the working length is considered an approximation. By examining the dimension listings on https://usseal.com/single-spring-mechanical-seal-dimensional-index/ you should find a seal that is close to the Working length you calculated from the above formula.
Measure the O.D. of the seat or measure the Bore the seat will press into. If measuring the Outside Dimension of the seat (as pictured) SUBTRACT approximately .016″ to account for the rubber squeeze required for the interference fit of the seat.
Once you know the above dimensions, look at the following index https://usseal.com/single-spring-mechanical-seal-dimensional-index/ and narrow down which seal is the one you want. The part number will be listed on the right hand side. There may several seals of the same type that vary by the materials of construction. You will want to know the elastomer type (Buna, Viton, EP) and the seal face materials (Carbon, Silicon, Tungston, Ni-resist, Ceramic). All of our single spring seals are made of stainless steel.
If you have any questions you can contact our inside sales staff at 714-361-1435.
We also have more detailed information on mechanical seals and their designs at www.mechanicalseals.net
There is no sealing device more expensive than a cheap one.
We are unique. Most distributors are tied to one major line and promote only that line. We offer multiple lines because no one sealing company is good at, or most cost effective in all the product segments they offer. Let us help you get the most for your money.
Is a single spring seal the best choice for me?
It all depends on the service you are placing your seals into. If your pump is just moving water than in most cases a single spring seal is what you want. 80% of the worlds pumps are pumping water. What does have to be considered is the quality of the water, does it contain, salt, lime, silt, sand, or other abrasives? If so a single spring seal can still be right for you, just make sure you order “hard faces”. If on the other hand, you are dealing with high heat applications (over 450F) or chemical applications anther seal will do a better job.