What is the highest temperature application for Simsite?
The highest temperature for our standard grades of Simsite is 150ºC. Our high temperature composite is good up to 210ºC. It is possible to make structural composites for higher temperatures; however, it gets very expensive.
Why should I use Simsite impellers in all my pumps?
Simsite impellers are hydraulically and mechanically superior to other impellers because they are 100% machined on the outside and inside. Simsite impellers are hydraulically superior to cast metal impellers because they are free from casting imperfections and have a much lower coefficient of friction.
Simsite impellers are designed to operate at maximum efficiency. The hydraulic design of each impeller is checked against performance data to insure proper operation of the pump. Should an engineering modification be required, the design of impeller can easily be changed to provide the customer with the best possible design for his specific application. Simsite impeller vanes are machined to maximize efficiency and provide the customer with the best possible vane shape for his particular service.
Simsite impellers are mechanically superior to cast metal impellers because they are light weight which reduces the static deflection of the shaft and because they are machined as opposed to being cast. Simsite impellers are approximately 1/6 the weight of bronze and stainless impellers. By reducing the mass of the impeller, you permanently alter rotor dynamics. When you reduce the weight of the impeller, you reduce shaft deflection which in turn reduces the radial forces in the pump. The result is that the entire rotating element lasts much longer.
Why should I use Simsite casing rings and wear rings in all my pumps?
Simsite casing rings seal very tightly into the casing ring landing areas. When the composite becomes immersed in the fluid it is pumping, it swells slightly, forming an excellent seal against the metal casing. This prevents the "wash out" of the landing areas that is the most common problem with pump maintenance. Also, Simsite Casing Rings and wear rings will not seize or gall; therefore, a tighter clearance can be maintained which reduces leakage though the rings and increases efficiency.
How do I set the clearance between the casing rings and the wear rings?
The clearances are set at the factory and Simsite impellers and casing rings are sold as a set whenever possible. The clearances between the impeller wear rings and the casing rings are already calculated when you purchase the rings and includes a clearance for swell and thermal expansion. However, if the customer wishes to machine their own rings, Simsite rings may be purchased undersize and oversize and the factory will tag the rings with the correct clearance.
Why should I use Simsite guide bearings whenever possible?
Simsite guide bearings will not corrode like bronze bushings. As the bronze bushings corrode and wear, they allow radial movement of the rotating element which causes premature failure of the wear rings and casing rings. In extreme cases, this radial movement can cause a shaft to break. Simsite bearings also have a lower coefficient of friction because of the composition of the material and because of the loose graphite that is embedded in the resin. The Simsite bearing not only protects the shaft but extends its life.
Yes, Simsite parts have loose graphite embedded in the resin system as well as structural graphite. This loose graphite is an outstanding lubricant and will permit a certain amount of dry running. We have had situations where the coolant was accidentally shut off to the Simsite composite guide bearings and the pump did not fail. If, however; the coolant is not restored to the Simsite guide bearings, heat will build up and when the temperature exceeds 260ºC the bearings will start to "char". Although the Simsite bearings will not melt or catastrophically fail like other bearings, the clearances will eventually open up in a dry operating condition until there is no more wall thickness available.
Yes, Simsite impellers can be repaired if the damage is not too extensive. This is a big selling feature. The product can be sent back for repair and overhaul. When a customer uses Simsite he substantially improves the time between overhauls. When you take into consideration the fact that the impeller can be repaired, then the customer's operating costs are lowered even more. All repairs to Simsite parts should be performed at the factory.
I already have bronze impellers and rings in my pumps -- shouldn't i use them up first?
No. Bronze impellers and rings in a salt water environment will contribute to the electrolysis inside the pump and you will jeopardize the life of your pump casing. If you replace the existing bronze impellers and rings with Simsite, you are replacing metal with an inert material and therefore you are reducing the amount of electrolysis in the pump. The bronze impellers and rings should be removed and used only as spares. In addition, as bronze impellers corrode they go into an imbalance situation which will cause premature wear on all other rotating parts.
If the wear rings swell slightly, how do you achieve the correct fit from the casing rings to the impeller wear rings?
All composites swell and are subject to thermal expansion. Simsite swells but very minimally. To compensate for this, the impeller is sold with the casing rings as a unit whenever possible. The clearances between the impeller wear rings and the casing rings are calculated and set at the factory. Unlike metallic rings which must maintain a certain clearance, Simsite rings will not seize and gall. Simsite rings are self lubricating and can endure a certain amount of dry running. If the clearances are accidentally set too close they will "wear in" with a smooth concentric pattern between the rings rather than seize or gall.
Why are Simsite impellers superior to metal impellers?
Simsite impellers are hydraulically and mechanically superior to metal impellers. They are hydraulically superior because they are machined as opposed to being cast and therefore are not subject to casting imperfections. Even an investment casting can only hold approximately 0.4mm (0.015") accuracy. Simsite impeller vanes can easily be modified to maximize efficiencies and provide the customer with the best vane shape for his particular service. Simsite impellers are mechanically superior because they are light weight which reduces static deflection of the shaft and will therefore reduce radial forces in the pump. Also, Simsite impellers will not corrode in a salt water or brackish water environment. Simsite impellers are machined from a solid block and because they are machined from a centre point they do not have the balance problems that a casting would have. When the customer receives a Simsite impeller it is balanced and remains balanced even after years of service.
Why shouldn't I purchase inexpensive "bootleg" metal impellers?
Most companies who sell "bootleg" impellers rough cast them or have metal impellers cast for them based upon a sample that is sent to them. The sample may or may not be accurate and most of these companies have little or no knowledge of hydraulics and have no way of checking the impeller for performance or efficiency. They often will follow the cheapest route which can mean disaster for the end user. Sometimes patterns which are close in design are substituted to save money in pattern costs and the result is the customer ends up with an impeller which has an incorrect performance. This can cause terrible problems such as recirculation damage, cavitation, radial reaction and vane tip frequency problems.
Often, cheaper grades of bronze or stainless steel are substituted to save money. The net result of this is that the impellers or rings wear out very quickly and the "customer" ends up paying more in the end, because his operating time is substantially reduced with an inferior product.
