If your process handles hazardous chemicals, you probably already know the safety basics: proper PPE, hygiene, housekeeping, and storage and disposal practices. And if something smells funky, don’t eat it.
When it comes to rotary valves, you’ll also need to consider air leakage, contamination, and corrosion. Let’s go over how to properly equip your valve against these issues.
Two types of airlocks, two types of leakage
To keep material flowing smoothly in the right direction, rotary airlock valves maintain a pressurized seal between the inlet and outlet flanges. If the seal is compromised, material can flow back up through the hopper and contaminate the air or surfaces in your facility.
Rotor-to-housing tolerances are key to maintaining the seal and preventing leakage. These tolerances are the gaps between the rotor tips and the valve’s housing, and they must be measured regularly to make sure they don’t grow too large.
Rotor tips do wear down over time, so when that happens, replace the rotor right away to prevent any dangerous leaks. You can configure valves and rotors with corrosion-and abrasion-resistant coatings to prolong their lifespan. Shaft seals should also be replaced regularly to prevent leakage.
That said, all rotary airlock valves have a small amount of air leakage — if they didn’t, they wouldn’t be able to rotate. When you’re ordering a new valve, your vendor should be able to calculate the amount of leakage and recommend the right airlock type, speed, size, and features. That may include a venting system to ensure the air is redirected safely.
Even small risks are magnified when you deal with hazardous chemicals, so your plant design should include proper ventilation and airlocks — that is, separate restricted rooms behind closed doors that receive air flow from other areas.
Lean, mean cleaning machine
It’s safe to say that you don’t want chemicals cross-contaminating or mixing with other materials in your facility. You’ll want to be diligent about housekeeping and choose methods that will reliably pick up dust, rather than dispersing it into the air. A common example is using wet wipes instead of dry wipes.
To minimize human error, make sure you have the right sanitary features built into your machinery. For example, U-shaped rotor pockets make it easier to clean your valve thoroughly, unlike V-shaped pockets that get material buildup in the creases. Glandless shaft seals and inboard bearings also prevent material buildup that could otherwise cause cross-contamination.
For applications that require frequent cleaning, we usually recommend a Quick-Clean rotary airlock valve to make your life easier. It streamlines and speeds up the steps needed to open up a valve and clean it, so housekeeping doesn’t get in the way of productivity.
Say no to corrosion
Chemical products can be sticky, cohesive, corrosive, or all of the above. Some chemicals can react with cast iron, so stainless steel is the safer choice for both sanitation and the longevity of your rotary airlock valve. You don’t want your machinery to develop rust that can contaminate the product. The valve should be polished to a 180-grit finish to further minimize material build-up inside the rotor pockets.
A coating called XTR-Coat was specifically developed for corrosive materials, so consider adding it to your valve if you need more durability with an anti-stick surface.
Find the right configuration
Your system is unique, and there’s no one-size-fits-all valve. It just takes one conversation for our experts to figure out which rotary valve, features, and coatings you need to keep your chemical conveying process safe and efficient. Give us a call and we’ll make things simple.
