Internal clearances on rotary valves are quite tight, thus they must be accurately machined. A.003″ –.005″ space between the tips and extremities of the rotor and the housing/head plate should be present in a smaller standard valve. Many valve clearances, on the other hand, are designed to satisfy the requirements of a certain application. For example, clearances may need to be bigger in applications with temperatures over 70°F to accommodate for thermal expansion. Contact Wm. W. Meyer & Sons to find out what internal clearances your valve was configured with before studying it.
It’s critical to keep clearances tight because this allows the airlock valve to successfully create a seal while yet allowing the material to flow between components of varying pressure. Rotary valves, like anything else, wear down over time. The qualities of the material passing through it, the features it was built with, the application it is used in, and the quantity of preventative maintenance conducted are all factors that influence the rotary valve’s longevity. Some valves can last for more than 30 years before they need to be replaced. Others must be changed or rebuilt on a regular basis. Valves that operate in harsh settings typically have a shorter lifespan.
There are two basic reasons why the clearances on a rotary valve should be checked. Either the valve is creating a noise that indicates the rotor is making contact with the housing, or there are signs of air seeping through the valve. However, before evaluating the clearances, numerous things should be done if a new valve is generating a high-pitched noise.
To begin, contact your valve’s manufacturer to determine what temperature your equipment was designed to withstand. Checking the clearances will not alleviate the problem if the material passing through the airlock is at a greater temperature than the valve was designed to handle.
After that, check to see if the rotary valve is level. On top and bottom, the airlock should be attached to a perfectly level surface. The rotor could come into contact with the housing or headplate if the internal clearances are depleted by even a tiny degree of torsion.
The same approach should be followed regardless of why the clearances need to be reviewed. Step-by-step directions are provided below, but before you begin, make sure you have all of the tools you’ll need to accomplish the task.
YOU WILL REQUIRE
Needle Nose Pliers in a Pair (or tool for removing chain links)
Screwdriver with Phillips Head
Set of.001–.015 Feeler Gauges
CAUTION: Only authorized personnel should perform rotary valve maintenance.
DANGER: Make sure the circuit breaker that controls incoming power to the gearhead motor is LOCKED OFF before working on the rotary valve.
- To gain access to the top and bottom of the feeder, remove it from the installation.
- Take the chain guard off.
- Disconnect the chain from the sprockets on the feeder.
- Remove any debris from the valve’s interior.
- Get the size feeler gauge that corresponds to the minimum clearance. Get out the.007″ feeler gauge, for example, if your valve should have clearances between.007″ and.009″.
- On the driving end of the valve, place the gauge between the rotor vane and the head plate. Then slide it down to the rotor’s shaft and back up to the rotor’s tip. Remove the feeler gauge and repeat the process on the valve’s blind end as long as the gauge moves freely.
- Rotate the rotor in the opposite direction it normally rotates to allow access to the next vane through the inlet. Step 6 should be repeated until all of the vanes’ ends have been verified.
- Now inspect the rotor’s tips. Slide the feeler gauge between the rotor’s tip and the housing to do this. Slide the feeler gauge all the way from one headplate to the other.
- Check the clearances on the tips of all the rotor vanes by rotating the rotor in the direction it normally turns.
- Use a feeler gauge that is.001″ larger than the clearance’s highest point. So, if the valve clearances should be between.007″ and.009″, take remove the.010″ feeler gauge.
- Attempt to put the.010″ feeler gauge between the rotor’s ends and the headplate, as well as between the rotor’s tips and the housing. If the feeler gauge fits, it means the housing and headplate or the rotor have begun to wear down.
- Now go to the outlet and verify the clearances.
- Place lifting lugs in the inlet flange’s bolt holes. Place a strap through the lugs and slowly lift the valve using a hoist.
- Reverse steps 5-11 for the discharge flange.
MAKE SURE THE CHAIN, INTLET, AND OUTLET GUARDS ARE IN PLACE BEFORE APPLYING POWER TO THE VALVE. THE VALVE’S INTERIOR CANNOT BE EXPOSED IN ANY WAY.