NESHAP stands for National Emission Standards for Hazardous Air Pollutants (NESHAP) and are standards set by the EPA for hazardous air pollutants. These emission standards are the legal requirements governing air pollutants that are released into the atmosphere. Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources over specific time frames.
In the past, many vapor degreasing companies used TCE (Trichloroethylene), or 1.1.1 or Trike, or TriChor in their vapor degreasing operations. And these chlorinated solvents along with PERC (Perchloroethylene) and methylene chloride are regulated solvents under NESHAP….and soon nPB will be as well.
In order to properly use these vapor degreasing solvents, certain vapor degreasing equipment features are needed to minimize the emissions. Note: this information is not meant to be a comprehensive list of vapor degreasing features, nor is it meant to be a detailed discussion of NESHAP and solvent practices. The intent is to articulate some of the vapor degreasing equipment features that make a vapor degreaser NESHAP compliant.
The most common NESHAP solvent containment features on a vapor degreaser are:
1. A SLIDE LID
Older vapor degreasers used to use a pull-off lid. The act of lifting and pulling off the lid from the top of the degreaser can cause solvent vapors to be pulled past the refrigeration coils and released into the open air. A slide lid allows the vapor degreaser to be opened without creating a vacuum that pulls the solvent out through the top.
The ULTRA™ systems have the option of a manual or automated slide lid.
2. SECONDARY REFRIGERATION COIL
Older vapor degreasers were created with a primary refrigeration coil for solvent containment. But to be NESAHP compliant, the vapor degreaser will need both a primary refrigeration system AND a second set of refrigeration coils usually known as a secondary refrigeration system. Other common terms for the secondary refrigeration coil/system are Zero Coil, or Sub-Zero. The reason for the “zero” is that the secondary refrigeration system operates at below 0°F – usually around -20°F.
The ULTRA™ systems all have a subzero, secondary refrigeration system- which is a continuous coil (which reduces possible leak joints) and is solid stainless steel. The ULTRA™ secondary refrigeration system is standard on every unit and runs on standard R404A refrigerant.
Also, worth noting, the secondary refrigeration coil really goes a long way to reducing solvent emissions with the new generation fluorinated solvents that are replacing TCE and nPB.
3. PRIMARY REFRIGERATION COIL
The first generation of vapor degreasers manufactured in the 1960s did not even have primary refrigeration. The solvent vapor was allowed to boil directly into the atmosphere through the open top vapor degreaser. Maya Angelo said, when we know better, we do better. Now we know better, and so we are doing better. The primary refrigeration coil was added to contain the solvent vapor in the tank – thus reducing solvent emissions AND saving significant cost in solvent loss reductions. The primary refrigeration system runs at 40°F.
The ULTRA™ primary refrigeration system is standard on every unit and runs on standard R134A refrigerant.
4. 100% FREEBOARD
The next feature that makes a vapor degreaser NESHAP compliant is it has a greater than 100% freeboard. What this greater than 100% freeboard means is that the distance between the very top of the vapor degreaser measured to the center coil of the primary refrigeration coil needs to be equal to or greater width of the tank. So, if you have a vapor degreaser that is 30″ wide. The length from the middle of the primary refrigeration coil to the top of the tank needs to be 30″. What this means that as a vapor degreaser gets wider the vapor degreaser needs to get taller to meet NESHAP standards.
The ULTRA™ freeboard ratio is always greater that 100% and is usually closer to 120%.
5. Automated Basket Handling for Automated Part Processing
One of the most effective ways to comply with NESHAP regulations is to install an automated basket handling system (a.k.a. automated hoist, automated lift) onto your vapor degreaser.
NESAHP stipulates a certain rate which the basket must move (both vertically and horizontally) to minimize solvent emissions. The requirement for part basket movement is 11 feet/minute. (To be honest this feels quite slow) but this slow movement reduces the solvent vapor agitation, and thus reduces the possibly of the vapors being emitted out the top of the vapor degreaser.
NESHAP also stipulate the part basket needs to have adequate draining time prior to removal from the degreaser and that the parts being cleaned do not absorb the solvent and thus allow the solvent to flash into the open air once removed from the unit.
In essence it is very difficult for a manual operator to comply with the part basket handling requirements (impatience is really the issue as dwell times, solvent flash off times, reduced movement times through the various zones of the degreaser can make part processing tedious for a human operator).
ULTRA Automated Basket Handling Systems allow you to program the part processing recipe to meet NESHAP requirements while ensuring dwell time, solvent flash off / draining times and ultrasonic immersion times are consistent each and every part basket processed.
Post by – Reliance Specialty Products, Inc. – vapor degreasing and solvent cleaning experts that manufacture both vapor degreasing equipment and vapor degreasing solvents.