Problems & Solutions hero image

Problems & Solutions

Same problem, different solution

With more than 200 years of experience combined, our team can find a custom solution for every problem you may have with an airlock. It's all about customization. Here are some of the common problems our customers face, why they happen, and how we can help.

Airlocks are our expertise

Blow-By

Blow-By
Overview
Problems
Solutions
The amount of air that escapes between the airlock rotor and housing.

Excessive blow-by can suspend material above the airlock, creating inefficiencies in the pneumatic line and a loss of product flow. In applications with abrasive materials, it can also be a catalyst for premature wear in the airlock due to the excessive vortex of air swirling the product in and through the unit.

The solution falls into two basic categories:

1) Design Modifications

Examples of design modification include, but are not limited to:

- Canted rotor

- Beveled vanes with reduced land widths

- Better manufacturing / engineering procedures. Rotary Airlock re-engineers by minimizing stacked tolerances which allows us to rebuild the airlock to closer tolerances, reducing blow-by and extending the life of the airlock

- Rotary Airlock builds new rotors which helps eliminate loping

- Bearing and seal upgrades are also solutions for preventing blow-by

2) Material Changes

Material changes include chrome, chrome oxide, AR 400 or AR 500 added to strategic points of wear, 41140 pre-hardened shafts, stellite, nibore, tungsten carbide and teflon

Leaking Seal

Leaking Seal
Overview
Problems
Solutions
The failure of the seal to maintain the pressure differentials between the inside and outside of the airlock.

As the seal begins to wear and give way, it allows the product and air to escape the lock. This causes the product to leak into the atmosphere unless there are other barriers (i.e. the bearings) to prevent it. Furthermore, if the escaping product comes in contact with the bearing, as in an inboard bearing airlock, premature failure will result. If neglected for too long, a failed bearing will drop the rotor into the housing causing additional damage to the bore.

We offer a number of seal installation modifications. The adaptation varies between various makes and models. Some common elements are:

1) The use of a seal protector or shoulder.

2) We have the ability to design a seal specific to your application, utilizing a customized shaft.  This solution offers superior protection against migration of product into the seal area.  There is no need for air to be run to the vulnerable seal area when using this solution.

Note: Air supplies not only need to be maintained, but are also subject to fail. The failure could be the result of an interrupted air supply of loaded up lantern ring. If failure occurs in this instance, the shafts can be scored and bearing will fail.

Corrosion

Corrosion
Overview
Problems
Solutions
A gradual destruction of metal by chemical reaction with its environment.

Corrosion occurs when the material of a lock, i.e. cast iron or mild steel, reacts with the product itself or the moisture in the product, causing the lock to rust and corrode.

Switching to various types of stainless steel or plating can help prevent most forms of corrosion. Design changes in the bearing and seal area can prolong bearing and seal life.

Caking or Sticking

Caking or Sticking
Overview
Problems
Solutions
The product is sticking to itself and / or the airlock. Stated another way, adhesion and / or cohesion of the product being conveyed. Most commonly found in products with high moisture content.

Adhesion can be caused by the surface of the housing and rotor tips being rough, causing the product to stick to the surface instead of sliding off. The product also can start hanging in the V of the rotor pocket or other sharp corners as is the case with a closed rotor where the sides of the vanes meet the shrouds.

Cohesion is the product sticking to itself. This can occur independently of adhesion, but is often aggravated or accelerated by adhesion. With cohesion, the resulting build-up in the housing may eventually seize the rotor. At a minimum, this can cause reduce flow capacity, resulting in poor airlock performance.

Various forms of polishing and plating can be introduced to reduce adhesion. Open rotors are often employed to eliminate corners. Radius pocket rotors are sometimes used. Bevels and knife edges are often added to the vanes. In the case of a closed rotor, this process is also practical for the shrouds as well.