Rotary Valve Bearings and Endplates

BEARINGS

The sealed-for-life deep groove ball type bearings are some of the most commonly used bearings in rotary valves. Grease filled bearings that are sealed using neoprene or similar seals are appropriate for temperatures up to 300℃ for high temperature applications. The bearings’ temperature capability can be improved by the use of different materials and lubricants. Generally, the size of the bearings may be associated with the size of the rotor shaft. In other words, their size is dependent on the rotor shaft size. The bearings are susceptible to product contamination. Outboard bearings and inboard bearings are the two distinct configurations applied to a rotary valve’s endplates.

Operating Speed

Rotor speed determines the throughput rate. It is important to run the rotary valve at the correct speed to obtain maximum efficiency while meeting the required capacity. Rotor speed of a rotary airlock valve is generally determined with respect to bulk density and particle size of handled material, required throughput, pressure or vacuum level at inlet or outlet of the rotary valve and similar process data.

ENDPLATES

The endplates of the rotary valve must be precision machined. It is on the valve’s endplates that the bearings are placed. The endplates are also known as side covers. The main function of the bearings in a system is to facilitate the rotation of the valve’s rotor. The bearings’ setup on the housing endplates can be configured in two distinct ways namely, inboard bearing endplates and outboard bearing endplates. The design of the housing endplates is solely dependent on the aforementioned configuration.

Inboard bearings

This is a descriptive configuration of how the bearings are positioned on the endplates. Slightly protruded endplates are used for this configuration and are sometimes considered as flat endplates. If the bearings are directly positioned on the housing endplates, the bearings setup is known as inboard, hence the name inboard bearings. This setup provides greater risks such as contaminating the bearings which may lead to premature breakdown when the seal fails.

Inboard bearing rotary valve endplate

Outboard bearings

In this configuration, the bearings are not directly positioned on the valve’s endplates, instead they are situated farther out on the endplates in comparison to inboard bearings. This configuration uses more protruded side covers, there is a gap between the seals and bearings. This configuration offers lesser risks compared to inboard configuration. In the case where a seal fails, the bearings are not compromised. The setup offers lesser chances for a combustible dust stream to be ignited if ever the bearings overheats. The other advantage of this setup is that if high temperatures are involved, the bearings are not easily affected

Outboard bearing rotary valve endplate

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