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General Filter Questions

Q:  What is inertia separation?
A:  Separation by inertia is the working principle of the Andreae Filter.  Airborne paint particles (overspray) enter the Andreae Filter to undergo several radical directional changes and settle out of the airflow to accumulate in the holding pockets.  The holding pockets retain the paint particles outside of the air stream.

Q:  Does the Andreae Filter only work with paint?
A:  The Andreae Team range of filters are made to capture any wet solids or liquid particles contained in an air stream:  high solid enamels, baked and air dried enamels, glues, oils, stains, lacquers, fiberglass, epoxies, asphalts, clear coats, tar, teflon, etc.

Q:  What is the difference between the Andreae Standard and the Andreae High Efficiency and how do I choose?
A:  The Andreae Standard (STD)is a single stage filter with 98.2% paint arrestance efficiency.  The STD has a holding capacity of 4lbs/sf.  The Andreae High Efficiency (HE) is a two-stage filter with 99.4% paint arrestance efficiency.  The HE has a holding capacity of 5.3lbs/sf.  To decide which filter is best for your application, first consider the number of stages and efficiency required to filter the coatings applied.  Second, consider particle size.  Smaller particles such as air-dry enamels are best filtered through the HE, whereas fiberglass and frit are best filtered through the STD.  Also consider tackiness of the coating such as in stains and adhesives which are best filtered through the STD.

Q:  I want to change my filter media to the Andreae.  Do I need to alter my filter frame?
A:  Generally, the Andreae Filter will fit in any channel frame without modification.  Measure the width and length inside the frame to determine actual filter size.  Exhaust walls with 20x20" and 20x25" cells require a one-time installation of the Andreae Wire Support (provided free of charge for all qualifying conversions).  Contact your distributor to make the change (or Andreae Team for a distributor near you).

General Floor Paper Questions

Q:  Is Andreae Floor Paper flame retardant?
A:  Yes, Andreae Floor Paper is made of flame retardant paper.  Excellent flame resistance (T461cm-00), approved by the Physical Properties Committee of TAPPI, improves the safeguarding of persons and property from hazards arising from fire.  Andreae Team, Inc. requires their paper suppliers to meet or exceed the TAPPI Standards to ensure quality in every roll of Andreae Floor Paper.

Q:  Will Andreae Floor Paper reduce rejects in our paint booth?
A:  The vivid bright white paper of Andreae Floor Paper illuminates booth visibility and minimizes shadows, thus reducing rejects.

Q:  Can we cover our walls with Andreae Floor Paper?
A:  Although there has been some instance of this application in Europe, we have not heard how successful the application was.  Therefore, we cannot recommend Andreae Floor Paper to be used as wall covering.  If anyone has tried this application (successful or not)please let us know your results!

Q:  How do you adhere the paper to the floor?
A:  We recommend a heavy duty industrial tape to adhere Andreae Floor Paper to the floor.  However, 2" standard masking tape has been used with success.  Start with a clean floor.  Using a tack cloth, wipe the area of floor to be taped and adhere the tape to the paper and floor.  Unroll the floor paper to desired length and cut.  Again, using the tack cloth, repeat process to tape the end of the paper to the floor.  Tape down seams as desired.


Q: Does it matter if the filter is overstretched?
A:  The accordion shape of an Andreae Filter concentrates a large number of pockets and holes per square foot.  Overstretching an Andreae Filter dramatically increases the static pressure and reduces filter life.  Ideal installation is 8 pleats per foot.  Most Andreae Filters are equipped with an extension limiter to prevent over-extension.

Q:  Why is a high holding capacity essential?
A: Simply put, the greater the holding capacity of a filter... the longer the life of the filter.  The working principle of Andreae Filters causes captured overspray particles to be deposited outside of the airflow into deep holding pockets.  The larger the pocket, the better the holding capacity of the filter.  The Andreae Filter has 8 deep holding pockets per linear foot.

Q:  How can I prevent uneven airflow across my filters?
A:  Inconsistent airflow across the exhaust wall is a common problem in paint booths.  Mesh, fiberglass and polyester filters capture overspray on their face (or front of the filter), decreasing the life of the filter.  This is most prevalent in areas directly behind the direction of spray.  Only portions of the filter become loaded which causes airflow to deviate toward the peripheral areas of the exhaust wall.  Andreae Filters are designed to prevent face-loading by loading back to front.  This is attributed to the Andreae structure and working principle, inertia separation.


Q:  I cannot figure out how to get the wire supports in place!
A:  Wire supports are used for 20x20" and 20x25" filter cells in an exhaust wall.  The easiest way to install the wire support is to hold the support in front of the cell (ensure the straight tines are oriented vertically)and tip the top tines toward the cell.  Hook the tines under the top flange of the back wall and slide the tines as far up as they will go.  This should allow enough space at the base of the cell to push the bottom tines past the bottom flange of the back wall.  The support is now secure and can be slid around to center the support in the cell.  Adjust the L-shaped tines (sidewall supports) to allow for 1/8" between the tine and the sidewall.  This one time adjustment will allow space for the end filter pleats to tuck behind the tines.  Once the supports are in place, there is no need for further adjustment.

Q:  My booth does not have end clips on the side walls.  How can I use the Andreae Filter in my exhaust frame?
A:  Three simple elements constitute the Andreae Filter frame:  a U-shaped beam as the upper part of the frame, an L-shaped beam as side and bottom parts of the frame and the L-shaped side clips.  The first and last pleats of the Andreae Filter are inserted behind these clips to contain the filter and seal the exhaust wall properly.  Side clips can be added to existing exhaust frames by bolting a 1x2" angle bracket made of sheet metal to the end walls.  See our installation instructions for a diagram.

Q:  My filter sags in the booth.  What is causing this and how can I prevent it?
A:  The Andreae Filter is designed to withstand any liquid application.  If the filter is overloaded, it may begin to sag due to the weight of the overspray collected (in excess of 4lbs/sf for the STD or 5.3lbs/sf for the HE).  To prevent overloading the filter, consult the pressure guage.  The recommended maximum pressure drop is 0.51 in wc.  Although 1.03in wc is possible with an Andreae Filter, most fans will unload above 0.51in wc.  Ideally, you want to achieve the highest pressure drop possible to prolong the life of the filter.  Mark your pressure guage when loss of airflow occurs to indicate when the filter needs changed.  Another cause may be change in airflow.  Has anyone changed the fan to increase airflow?  Although rare, we have seen an occurrence where the airflow was increased from 150fpm to 400fpm to make the painter more comfortable.  This resulted in the filters being sucked into the plenum.  Bottomline, monitor the pressure guage.


Q:  Can Andreae Filters be used in the Aerospace Industry?
A: Yes.  Andreae Filters are compliant with 40CFR63 Subpart GG (NESHAP for Aerospace) as prefilters (stage 1 of a 2 stage system or stages 1 & 2 of a 3 stage system).  The scope and application of Test Method 319 states that "if the final stage has been shown to meet the filtration requirements, then the final stage in combination with any additional paint arrestor stages also passes the filtration requirements."  Therefore, prefilters need not be tested using M319 and can be used in combination with a certified final stage.

Q:  How are Andreae Filters tested?
A:  Andreae Filters are tested by Air Filter Testing Laboratories using AFTL A206-84, Paint Arrestor Device Removal Efficiency, Paint Fraction Weight Arrestance with methods consistent with ASHRAE 52.1-1992, "Gravimentric and Dust-Spot Procedures for Testing Air-Cleaning Devices Used in General Ventilation for Removing Particulate Matter, June 4, 1992" as per the specific paint test parameters outlined in the EPA requirement found in 40CFR63.

Q:  What is BACT?  GACT?  MACT?  RACT?
A:  These are regulatory tools used to address air quality problems.  BACT is defined as the Best Available Control Technologies.  Permitting authorities may determine BACT on a case by case basis.  BACT standards take into account cost and availability while allowing for area sources to use alternative methods, systems and techniques to comply with maximum achievable HAP emission reduction.  California BACT standards are modeled after the lowest achievable emission rate (LAER), the most stringent emission limitation in practice.  GACT, Generally Available Control Technologies, are the most readily available guidelines that have the least amount of burden for record keeping, yet provide effective HAP emission control.  GACT standards are applied to area sources that produce less than 10 tons/year individual HAP such as small auto body refinishing shops, cabinet shops, etc.  Major sources of HAP emissions (>10tons/yr)are typically regulated with the Maximum Available Control Technologies, MACT, such as in the Aerospace Industry.  MACT standards achieve the maximum level of HAP emission reduction.  RACT is defined as Reasonably Available Control Technologies.  This is the most basic obligation for any source of HAP emissions.

Q:  What documents must we keep on file for inspection?
A:  Where exhaust filtration is concerned, area sources must maintain on file filter efficiency certification, MSDS and (required by some inspectors)the installation instructions and spec sheet.  We also recommend you keep our Disposal and Test Method Compliance statements. 

Q: Do Andreae Filters have a UL2 rating?
A:  Andreae Filters are not UL2 classified.  Underwriter's Laboratory (UL)states that a Class 2 certification only applies to clean filters because the combustibility of particulate accumulation in the filter has not been measured in the test standard.  A 1996 Letter of Interpretation states that "an employer who complies with a consensus standard, such as NFPA 33, rather than an OSHA standard in effect at the time of inspection and clearly provides equal or greater employee protection will not be cited."

Q:  What are the disposal requirements for Andreae Filters?A:  Andreae Filters are non-hazardous and biodegradable.  Loaded overspray collectors must be disposed of in the same manner as any paint-laden waste material.  The proper disposal procedures are contained in OSHA Standard 1910.107, NFPA Standard 33 and the Code of Federal Regulations 40CFR63.  Federal, state and local codes and regulations must also be followed in establishing where and how to dispose of this material.  See our Disposal Compliance for more information and contact you local waste management or permitted landfill for additional instructions.


Q:  Do Andreae Filters work in both cross-draft and down-draft booths?
A:  Yes, Andreae Filters can be used in any type of dry filter exhaust wall. The filter frame must be compatible with the Andreae Filter and may require minor modifications.  See our installation instructions for additional information.

Q:  Our booth is losing airflow.  What could be the cause?
A:  Typically, fans unload (or lose the ability to move air) because the filter is overloaded or the fan has a problem.  First, ensure the Andreae Filter is installed at 8 pleats per linear foot.  Next, install a pressure guage to measure airflow across the clean filters and mark the point just before losing airflow to indicate when the filters need to be changed.  Choose a fan that is capable of pulling up to 1in wc across the filter.  Our recommended maximum pressure drop is 0.51in wc because some older fans will unload above this pressure.  However, the Andreae Filter is capable of handling pressure up to 1.03in wc.  If your fan is sized to handle greater pressure, we encourage you to try to achieve the highest pressure possible to get the maximum life out of the filters.  Ensure the fan motor, belt, blades, etc. are maintained properly.  Clean the fan periodically to remove particle build up.

Q:  We have excessive paint in the plenum.  What causes this?
A:   Over time, particles will build up in the plenum.  Regardless of filter media, the plenum should be cleaned periodically since exhaust filters are not 100% efficient.  For example, if 100 gallons of coating is sprayed into a 98% efficient filter, 2 gallons will escape.  Prevent excessive build up in the plenum by maintaining your filters properly:  install the filters as per manufacturer instructions and monitor static pressure drop across the filters to ensure they are not overloading.  A general rule of thumb is to clean the plenum annually or more frequently in high use booths.

Q:  Paint is migrating out of my filters.  How can I prevent this?
A:  The migration phenomenon is common when slow-drying coatings are used with mesh filters.  The airflow will pull particles trapped in the mesh back into the air stream.  Consequently, the particles already deposited will again be airborne and migrate through the system.  To prevent this from happening, change to an Andreae Filter where the paint particles are deposited in holding pockets outside of the air stream.

Q:  My HE filter hardens in the booth making it difficult to remove.  What can I do to ease removal?
A:  When the paint dries in the filter, it may create a very hard accretion.  In this case, the filter may be difficult to remove because the polyester sticks to the frame of the booth.  To prevent this, coat the frame with a non-hazardous grease before installing the clean filter.

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