Expanded Seal Flexibility with U-Plus™ Brackets

Viking Pump’s new  generation of pumps (sizes H-QS in steel and stainless steel) offer a wide array of benefits that the previous alloy pumps could not, particularly in the area of sealing flexibility. These new pumps increase the number of sealing options possible in one pump, while at the same time reducing cost and lead times.  

The bracket is the large component behind the casing which has the rigid cast-in foot that the pump is mounted on. It houses the inboard shaft support bushing, the seal gland and the outboard thrust control antifriction bearing housing.

By combining features of the existing 123A, 127A and 724 Series™ pumps, we are able to provide patented features that did not exist before, like the ability of one pump to accept either stuffing box seals or behind-the-rotor seals.

Now THAT’S getting more bang for your buck!

The new 123C and 127C Series™ models are not jacketed, but Viking Pump also offers 223C and 227C Series™ models with jacketed U-Plus™ brackets to allow circulation of steam or heat transfer fluids to melt ambient-temperature solids in the pump, like resins, pitch or chocolate. These models have the option of adding jacketed heads without relief valves, or adding jacketed relief valves on non-jacketed heads.

Stuffing box seals may be either packed glands, O-Pro® Guard seals, component mechanical seals, cartridge mechanical seals or cartridge multiple-lip seals, each of which has different uses and advantages.

• Component mechanical seals are the least expensive type of seal and have the widest availability but require care to install without damaging the seal faces. Flush lines from the discharge port to the seal area of the bracket are standard with these seals to flush away solids and cool the faces.

• Cartridge type mechanical seals are constructed as a one-piece preassembled seal to allow for easy installation in the pump stuffing box. The rotating portion of the seals are setscrewed to the shaft outside of the stuffing box. Because the seal faces of the cartridge seal are not individually installed or handled, seal failures occurring because of improper installation or handling are minimized. Single or double cartridge seals can easily be adapted to an API seal plan with barrier fluid to minimize fugitive emissions escaping from the seal. Cartridge-type lip seals are available that enable replacement of individual lips to minimize life cycle cost of the seal, and are highly successful in some difficult applications like pumping adhesives.

Mechanical seals mounted directly behind the rotor were previously only available on the stainless steel 4724 Series™ and the cast iron 4124B Series™ pumps. They prevented any liquid from entering the bracket and were often used for liquids that tend to set up between the bracket bushing and stuffing box seal. Now they are available on all Next Generation models with U-Plus™ brackets, sizes H-QS, including Type 9 PTFE wedge seals for corrosive liquids to 25,000 SSU (5,500 cSt).

The bearing housings have not changed from the original 123A/127A models and are threaded on to allow adjustment of rotor end clearance within the pump. This enables users to rotate the bearing housing to easily adjust from very low to very high viscosities (or vice versa) without loss of efficiency, or to adjust for rotor end wear over time to maintain pump efficiency without having to replace the rotor/shaft.

A key benefit of the U-Plus™ Bracket is that if one type of seal does not satisfy the users’ expectations for seal life or leakage prevention, it is easy to change to any other type of stuffing box or behind-the-rotor seal. The brackets are retrofittable onto existing Viking 123A/127A/223A/227A pumps, and have common mounting dimensions.