Venting

The environment in the area of an industrial cleaning system is often not a “healthy” one for personnel or equipment.  Caustic and acidic cleaning chemistries rise as mist above cleaning processes along with humidity and heat.  Although our first thought is to protect personnel from these hazards, the equipment can also suffer serious consequences as a result of long term exposure to the unfriendly and corrosive environment.  Although the problem is relatively easy to grasp, solutions are a bit more difficult and often prove to be more challenging than one might expect.

Everything would be rather simple if we could just build a box around the cleaning system to contain harmful effluents.  There are machines which accomplish this with mechanized material handling behind enclosures.  This, however, is not a universal solution as it is frequently necessary to have access to the machine as well.  The difficulty is to provide the necessary access to the process while sufficiently isolating it from the surrounding environment.  The answer is to provide a means of venting that will capture and direct the harmful fumes away while still providing access to the process.  This is accomplished in different ways depending on the nature of the process and the design of the equipment.  Vents along the back or side(s) of the cleaning tank are probably the most simple and common form of venting.

In the case of smaller tanks, lip vents may be an effective solution to providing the required venting.

Larger tanks require a different approach to venting.  The most common type of vent consists of a tower placed behind the tank as shown below.  A simple vent tower, however, may not be effective in totally capturing all vapors.

Although used in many cases, the simple vent tower has some problems.  In order to be effective it is almost imperative that the exhaust be powered.  As the front to back dimension of the process tank increases, the amount of exhaust required for effective venting rises exponentially.  Of course, as the amount of air vented is increased, the amount of makeup air required increases as well.  Makeup air, especially if it needs to be heated or cooled, can be more costly than using a more efficient venting option.

The efficiency of the venting system described above an be greatly increased by adding a blower to direct fumes to the vent as shown below.

Obtaining optimum results with a blower system requires careful adjustment to assure that the collection tower can accept the flow produced by the blower.  Too much blower air can result in reduced effectiveness as shown below.

There are, of course, other venting options in addition to the above but these are the most commonly used.  An upcoming blog will address the issues of handling exhaust.

–  FJF  –