Installation procedure for Exhaust Gas Purifier / Scrubbers
Click to download the PDF of the Installation Procedure.

The Exhaust Gas Purifier / Scrubber should be located as close to the outlet of the engine exhaust manifold (or turbocharger) as possible. The purifier should be located no more than 30” (760 mm) from the engine exhaust manifold outlet (or turbocharger). In addition, the exhaust gas purifier should be located between the engine exhaust manifold (or turbocharger) and the muffler. In order to eliminate harmful diesel exhaust gas pollutants, as much exhaust heat energy as possible is required for proper purifier operation. The hotter the exhaust gases at the inlet cone of the purifier, the more heat energy is available to “oxidize” (reduce) harmful exhaust gas pollutants. The Exhaust Gas Purifier can be installed vertically or horizontally. Do not allow the exhaust gas purifier to contact any structural members of the vehicle or equipment. Avoid locating the exhaust gas purifier in close proximity to electrical components, fuel lines, fuels tanks or any combustible materials.If it is impossible to locate the exhaust gas purifier between the engine exhaust manifold (or turbocharger) and the muffler, then we recommend installing the purifier immediately after the muffler. However, we recommend that the full length of exhaust pipe, the muffler and the purifier be insulated with a commercially available heat wrap tape. Contact the sales office for additional heat wrap tape information. Alternately we do supply a large variety of combination purifier mufflers for Atlas Copco, CASE, Caterpillar, Bobcat, Gehl, Genie, Honda, International, Ingersol Rand, JCB, etc. In some circumstances the use of purifier mufflers may be the only option available. Contact the sales office at 1-(800) 233-6539 for additional information. To install the Exhaust Gas Purifier / Scrubber cut the appropriate length of exhaust pipe from the existing engine exhaust system. Generally the pipe length to be cut is approximately 1.5” (38 mm) to 2.5” (64 mm) less than the overall length of the exhaust gas purifier. The required pipe length to be cut will vary depending on the particular exhaust purifier model. Alternately measure the distance between the stop pins located on the purifier inlet / outlet cones to determine the required cut length.
Use the directional flow arrow located on the exhaust gas purifier label to orient the exhaust flow direction of the Exhaust Gas Purifier. Install the exhaust pipe into the exhaust gas purifier inlet/outlet cones until the exhaust pipe butts up squarely against the stop pins of the inlet and outlet cone.
Once the Purifier is installed into the exhaust pipe use wide band muffler clamps or flat band clamps to secure the purifier. We recommend using “Easyseal,” “Torctite,” or “Accuseal” wide band clamps (manufactured by Nelson, Donaldson, Riker, Stemco, etc…).Wide band clamps are readily available at local truck exhaust parts or truck parts jobbers/suppliers. Alternately arc or mig welding can be used to weld the exhaust purifier inlet/outlet cone directly to the engine exhaust pipe. Use type SS309 filler wire or rod with a DC current of approximately 40 to 45 AMPS maximum. Do not weld onto any other part of the purifier or purifier body.
Torque the wide band muffler clamp bolts to the correct torque specification. Usually 45 to 55 foot pounds torque is sufficient. Start and idle the engine for a period of 15 to 20 minutes. Re-torque the clamp bolts to the correct torque specification. Double check for any apparent exhaust leaks.
Once installation of the exhaust gas purifier/scrubber is complete, the engine exhaust back pressure restriction should be measured. Use a back pressure gauge/manometer (0 to 40” H20 range) to measure the exhaust gas flow restriction. Remove the 1/8” NPT brass plug located at the 1/8” NPT port on the inlet cone of the purifier. Install the metal probe of the exhaust back pressure restriction gauge into the 1/8” NPT port. Start the engine and operate the engine at high idle and load stall conditions. Measure and note the exhaust gas restriction at both high idle and load stall conditions. Ensure that the total exhaust gas flow restriction is within the engine manufacturers recommendations.

The Exhaust Gas Purifier / Scrubber is now ready for use, if you have any additional requirements, comments or questions please call the sales office at 1-(800)-233-6539.
Click here for detailed information on Foley’s exhaust scrubbers and purifiers, as well as diesel particulate filters.

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Great Tips on Helping You Maintain your Diesel Particulate Filter
4.1 DPF Maintenance Requirements
The following are maintenance requirements to follow for servicing the DPF. Due to large variations on operating conditions, the maintenance schedule may change slightly depending on the specifics of the application. Below in Table 4.1, are requirements to follow for servicing the DPF.




Every 50 hours of operation

Manual Back pressure Check

Operate the engine at high idle. At exhaust port upstream of DPF install manual back pressure gauge. Record results in a log sheet.

Every 200 hours of operation

Check for leaks

Make visual check of piping, fittings, clamps and gaskets in the exhaust system for exhaust leaks. Look specifically for evidence such as soot present near connection. Repair if necessary.

Every 200 hours of operation

Check Pressure Transducer

Remove pressure transducer and apply pressure to the line. Check line for leaks. Indicator lights must illuminate at a specified back pressure.

Every 1000 hours of operation

Filter Cleaning

Conduct Level 2 Cleaning (See section 4.4 below for details)

Filter Cleaning

Conduct Level 1 Cleaning or Level 2 Cleaning according to guidelines in Table 4.2 below.

4.2 Manual Back Pressure Checks
When taking manual back pressure measurements, operate the engine at high idle. At an exhaust port upstream of the DPF install a manual back pressure gauge. Record results in a log sheet.
Table 4.2 – Manual Back Pressure Check


Filter Condition



DPF is damaged

Remove DPF and contact Foley Engines for further assistance

5-25″wc (2.5-6.25kPa)

DPF is clean

No action

25-40″wc (6.25-10kPa)

DPF is moderately loaded with soot and/or ash

Level 1 Cleaning  or Level 2 Cleaning is required within the next 50 hours of operation

>40″wc (>10kPa)

DPF is highly loaded with soot and/or ash

Remove DPF immediately and conduct Level 2 Cleaning

4.3 Level 1 Cleaning
4.3.1 Standard Design

Remove the DPF center-body using the quick-release clamps. Be sure to properly support the DPF upon removal as the filters are fragile and can break if dropped. Depending on the size of the DPF, this may take two people.
Attach to the filter inlet (sooted end of DPF), a vacuum which feeds into a high-efficiency particle arrestance (HEPA) filter making sure that all connections are airtight to prevent soot/ash from escaping before being forced through the HEPA filter.
Using compressed air (~80psi) blow the particulates/ash from the outlet end of the DPF towards the inlet of the DPF, through the vacuum and through the HEPA filter. The air gun should be held a minimum of 2 inches from the surface of the DPF to prevent damage to the filter itself.
Move the air gun around to ensure that all of the DPF channels on the outlet have been exposed to the compressed air. Compressed air cleaning should be performed for an approximate duration of 10 minutes.
Remove the HEPA filter and store away for re-use or dispose of if saturated with soot/ash.
Reinstall DPF center-body on given application and fasten securely using all applicable mounting hardware.
Perform a manual back pressure check at no load and high idle conditions to ensure that the Level 1 Cleaning reduced the backpressure build-up due to soot/ash removal. Back pressure should be less than initial back pressure reading before cleaning procedure.

4.3.2 Custom Design
The majority of custom DPF designs are developed to replace the original equipment muffler. The two most popular designs allowing access to the DPF for cleaning are shown in Figure 4.1 and Figure 4.2 below.

Figure 4.1 – Flanged Center-body DPF Muffler

Figure 4.2 –Bolted End-disc Custom Design 1 (See Figure 4.1)

Remove DPF muffler from application in the same manner as if removing original muffler. Be sure to properly support the DPF upon removal as the DPFs are fragile and can break if dropped. Depending on the size of the DPF muffler, this may take two people.
Remove DPF from muffler center-body by undoing the quick-release clamps or removing the bolts from the flanges in the center of the muffler.
Perform Level 1 Cleaning steps 2-5 inclusive of Standard Design cleaning instructions above.
Reinstall the DPF into the center-body of the muffler and secure it in place by either tightening the clamps or bolting the flanges.
Reinstall muffler into application in the same manner as installing the original muffler.
Perform a manual back pressure check to ensure that the Level 1 Cleaning reduced the back pressure build-up due to soot/ash removal. Back pressure should be less than initial back pressure reading before cleaning procedure. Custom Design 2 (See Figure 4.2)

Remove DPF muffler from application in the same manner as if removing original muffler. Be sure to properly support the DPF upon removal as the DPFs are fragile and can break if dropped. Depending on the size of the DPF muffler, this may take two people.
Remove bolts on muffler body end-disc and remove disc from muffler exposing DPF inside.
Attach to the muffler exhaust flow inlet, a vacuum which feeds into a HEPA filter and secure around the muffler inlet pipe to prevent soot/ash from escaping before being forced through the HEPA filter.
Perform Level 1 Cleaning steps 3-5 inclusive of Standard Design cleaning instructions above.
Replace muffler end-disc onto muffler and bolt to secure.
Reinstall muffler into application as installing the original muffler.

4.4 Level 2 Cleaning

Remove the DPF from the application. If it is a standard design, simply remove the quick-release clamps. If it a custom design DPF muffler such as Figure 4.1 or Figure 4.2 above, remove the DPF muffler in the same manner as the original equipment muffler. For removal of other custom designed filters, contact Foley Engines as necessary.
Place the DPF center-body, inside an oven or kiln ensuring that the inlet and outlet of the DPF are exposed (i.e. DO NOT sit the DPF vertically in the oven so that the DPF inlet or outlet filter faces are against the surface on which the DPF is resting).
Increase the temperature of the oven to 500*Cover a period of 1.5-2 hours.
Retain an oven temperature of 500*C for a continuous period of 4 hours to allow complete combustion of accumulated soot in the DPF.
Decrease the temperature back down to a temperature that will allow for safe removal of the DPF by hand.
Remove the DPF from the oven and perform a Level 1 Cleaning to remove the non-combustible ash content.
For standard DPF designs, reinstall DPF center-body into position on the application. For custom designs, either reassemble muffler by placing the DPF center-body into a muffler and clamping or bolting it into place, or reinstall the muffler end-disc by bolting it to the muffler.
For custom design muffler replacements, reinstall the DPF muffler back into the application in the same manner as installing the original equipment muffler.

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DPFs for Industrial Engines made simple
This Tech Tip was designed to answer many of the questions we have received from customers about DPFs when used in industrial applications on Perkins, Deutz, and Deere industrial engines.
What is a DPF?
A diesel particulate filter is designed to reduce particulate matter emissions from a diesel engine. Essentially it is a soot trap. In fact some manufacturers such as DCL have even labeled their DPFs as “soot filters” and registered the trademark.
Does it improve air quality?
Yes, a DPF improves the quality of the air by removing particulate matter. It does not make it safe to breathe though. Only a diesel oxide catalyst (DOC) by removing CO does that.
Do DPFs have a DOC component?
Most of those designed for use in off road applications in closed spaces do also have a DOC. On road trucks tend not to use a DOC with their DPF system especially in a line haul operation with high exhaust temperatures.
How Does a DPF work?
A DPF uses a honeycomb ceramic structure with a series of alternate tubes or channels. The tubes are plugged at opposite ends and the diesel exhaust gas enters through the open end of each tube. The plugged end of each channel forces the soot particles against the porous walls of the channels. The soot is burned off there and the gases such as steam and CO 2 pass through the adjacent exit tube.
What is passive regeneration?
Under high load conditions the exhaust gas temperatures are high enough to quickly bake off most soot or PM in the DPF. In other words, the exhaust gas temperatures clean the DPF of excess soot.
What is active regeneration?
Under conditions of low load such as excessive idling the diesel exhaust gas temperature is not high enough to burn off the soot so it accumulates in the DPF. This can create blockages. Some active systems including those made by Huss and Rypos Inc. use an electronic charge to clean the DPF. Other systems, notably those used in over the road trucks inject fuel into the exhaust system.
Cleaning a DPF
To ensure adequate performance a DPF should be cleaned at regular intervals. Mineral particulate and heavy metals from engine bearings and cylinder liners that get trapped in the lube oil will build up in the DPF substrate. This material is known in the aggregate as ash and will clog the space in the channels meant for the soot. Unlike soot, ash is inert and un-burnable. If left to accumulate it can damage the DPF. As a result it must be periodically removed from the DPF.
How does ash damage a DPF?
If the ash is not periodically removed from the DPF it will become hardened in the filter and hard to remove. Because ash is cooler than the other material in the DPF it can cause the brittle substrate in the DPF to crack. Once the ceramic in a DPF begins to crack, it will crumble, break up and blow out the exhaust stack. The expensive DPF can quickly become no longer serviceable and must be replaced.
How Do You Clean a DPF?
When DPFs first became common it was standard practice to simply blow them out with compressed air. Later, people used sand blast machines and thermal cleaning ovens to bake them clean. As the population of DPFs has increased manufacturers such as OTC Tools have developed dedicated cleaning systems. These systems are superior because the soot is not blown all over the shop floor and the oven cleaning temperatures are controlled to avoid damaging an expensive DPF.

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Easy to follow guide on ordering this wonderful device
Over the last 10 years we have become a major supplier, indeed one of the few US based suppliers, of diesel exhaust purifiers and exhaust scrubbers. These innovative products have helped us live healthier lives and improved our productivity. Without them, many construction projects just couldn’t be built. Yet many people are confused about how to order them. But Foley can make it easy for you. Here is all you need to do.
Diesel Exhaust Scrubbers: Four Easy Steps

Call us toll free at 800.233.6539 or, internationally, at 508.753.2979 and we will email you some general information about our diesel exhaust scrubbers and purifiers. This information package will contain some graphs showing the expected benefits. You might want to also look at our Tech Tip #26, Foley Engines Clean Air Tech Tip.
Let us know if you want the permanently mounted combination muffler/purifier or a one that installs with a clamp at the end of the tail pipe. There are pros and cons to each but most people order the clip on style for quicker shipment and to save perhaps $500.
If you wanted a combination muffler/purifier let us know the make and model of the machine you want to install it on as well as the existing muffler part number. For example, if you have a skid steer loader, you would advise that you had a Bobcat Model 843 (with a part number of 6559979).
If you wanted the equally good (but less expensive clip on style) just let us know the horsepower of the engine and the OD of the tail pipe. If you don’t know the horsepower of your engine, just give us the make and model of the machine instead and we can figure the rest out for you.

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Helpful tip on keeping the air we breathe nice and clean
Eliminate Carbon Monoxide Problems with Propane-Powered Forklifts
When propane-powered forklifts are operated indoors without proper fresh air ventilation, harmful levels of carbon monoxide (CO) may be found in the building. This can cause mild to severe nausea and poisoning. CO poisoning is brought on by incomplete burning of any material containing carbon, such as propane, gasoline, oil, natural gas, coal, or wood. CO is a colorless, odorless, tasteless gas that can only be detected with special equipment which measures air quality, or by observing poisoning symptoms in humans. Symptoms range from nausea, dizziness or headaches to brain or heart damage and even death.
When operating a propane powered forklift, the safest way to prevent CO threat is to tune the truck regularly, maintain it properly, and to add an exhaust purifier. Simple maintenance items such as an improperly gapped spark plug or a dirty air filter, can cause CO emission problems. A dirty air filter, as common as it may seem, can cause a problem due to lack of clean air mixing in during engine combustion.
For the inevitable CO problem, Foley Engines can equip your trucks with an Engelhard Exhaust Purifier. EngelHard Purifiers reduce up to 98% of harmful pollutants. For more information please call 800 233-6539. Foley Engines, the oldest engine distributor in the US serves the forklift and construction industries throughout the US. Foley is authorized in Engelhard, Perkins, Continental and Wisconsin.
The maximum allowable US OSHA concentration for continuous CO exposure in any eight hour period is 50 parts per million, according to federal law. Since the only warning you may have is someone getting sick or complaining about headaches, routine truck maintenance cannot be ignored.

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