MAINTENANCE TIPS FOR ROTARY VALVES – BACK TO THE FUTURE

“I study nuclear science, I love my classes I got a crazy teacher, he wears dark glasses Things are going great, and they're only getting better I'm doing all right, getting good grades The future's so bright, I gotta wear shades” 

--Written by Pat McDonald of Timbuk3

So welcome to the first edition of questions for the Editor.  To be honest, this whole concept terrifies me.  Not being asked questions, or potentially getting the answers wrong.  It’s just the whole concept of my kids now being able to compare me to Ann Landers.  They already call me the “Stay Puff Marshmallow Man”, and this may just be the final nail in the coffin that used to be my ego.  But here we go:

“Dear Ann, We have a process where we use a rotary valve as an airlock on an abrasive material and it occasionally wears out.  How can we best predict when this will happen so we can order a spare on time and don’t have down time?” 

- Anxious in Pittsburgh

You really need to talk to your folks about their choice in kid names.  Aside from that…I have nothing that predicts:  the weather, potential mood swings of my ex-wife or rotary valve wear.  Any one of these things is liable to change without notice, and past performance is no guarantee of future results.

BEST PRACTICES FOR ROTARY VALVE MAINTENANCE:

a) Measure the clearances of the rotary valve on as regular a basis as practical
b) Regularly document the pressure the system is running at.  If it starts to change or frequency of line plugs increase for no apparent reason, that may be an indication that a rotary valve is leaking more air.
c) Keep a spare valve in stock

ROTARY AIRLOCK VALVE WEAR IS LARGELY BASED ON 4 THINGS:

1) The abrasiveness of the material
2) The differential pressure across the valve.
3) The wear resistance of the valve
4) How fast the rotary valve is turning

Once a system is installed, the material is what it is. The differential pressure is only going to be reduced by either reducing the convey rate, shortening the convey run (and/or reduce the number of elbows) or increasing the pipe size (usually a whole new system is required though). As to abrasion resistance, that can be looked at but even here there are limits.

If the continued wear is not acceptable, then contact a system design engineer to look at changing the system design (Vacuum versus pressure or a dense phase/blow-pot based system).

That’s about the best we can do as far as future predictions.  While we do have Doc Brown working on a Flux Capacitor down in the R&D lab, until it gets finished you’ll just have to struggle by on your own McFly.

For more information about Rotary Airlock Valves Click Here.

Submitted By: Larry Eagan | Regional Sales Manager