p.1 

OAR Box 1147 

Prepped by Ollie Stewart 

Document Number: 

222) IV-E-96 

Docket Number: 

A-87-11 

Printed 4/22/2008 2:42:59 PM Sheet 222 of 242 
P.2 

MEMORANDUM 

A-87-11 

SUBJECT: Meeting with Bluecher Concerning a Filter Under Development for Use in 

Evaporative Canisters 

FROM: DanBarba, Mechanical Engineer 

Standards Development and Support Branch 

TO: Chester J. France, Chief 

Standards Development and Support Branch 

THRU: Glenn W. Passavant, Senior Project Manager 

Standards Development and Support Branch 

On October 10,1990 a consultant and a representative for Bluecher, a German filter 

company, met with EPA to discuss an adsorptive filter under development for use in 

evaporative system canisters. As discussed below, Bluecher claims that its filter has 

several advantages over the activated charcoal currently used in evaporative canisters. Such 

a filter, it was suggested, could relieve concerns by automobile manufacturers regarding 

canister size and placement for the proposed onboard refueling vapor recovery systems, 

which will be required to capture nearly three times the amount of vapor as existing 

evaporative canisters. 

The Bluecher filter, shown on the attached page, consists of small, spherically 

shaped adsorbers adhered to a porous polyurethane foam matrix. The spherical adsorbers, 

which can be made from either activated charcoal or a chemically activated polymer, are 

much smaller than the cylindrically shaped charcoal pellets normally used in evaporative 

system canisters and, as a result, surface area available for adsorption is increased. 

Although the use of smaller particles normally leads to poorer flow characteristics, the 

porous foam structure of the Bluecher filter allows the filter to breath easier, reducing 

pressure drop substantially. 

The following summarizes the major advantages of filter over conventional charcoal 

filter media. Included is a brief explanation of the mechanisms which give the filter its 

improved characteristics. 

- Decreased volume. Increased adsorption ability of smaller particles allows a 

smaller volume to be used. 

- Decreased weight. Porous foam matrix and smaller volume reduces weight 

- Lower pressure drop. Porous foam structure reduces air flow resistance. 

- Increased design flexibility. Filter may be cut and formed to any desired shape 

without appreciably affecting adsorptive efficiency of the filter. 

- Increased safety. Porous structure contains air pockets which reduce potential for 

"hot spot" formation and the ability of a flame to propagate within the filter. 
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Although the technology has been used succesfully in several industrial 

applications, Bluecher has not tested the filter to any extent in evaporative or onboard 

canisters. Therefore, we have asked Bluecher to provide EPA with samples of both the 

charcoal and polymer filters for possible in-house evaluation. 
Bluecher Filter 

Sample Filter 

Polyurethane Foam 

Spherical Adsorbers 

(Activated Carcoal or Polymer) 

P 
Bluecher Charcoal Filter 

Sample Filter 

Polyurethane Foam 

Spherical Adsorbers 

(Activated Charcoal) 
r 

P.6 

BLOCHE R 

A SYSTEM FOR THE CONTROL OF 

VEHICLE EVAPORATING AND 

REFUELING EMISSIONS 

August 1990 Number 1/90 

BACKGROUND •M BMa »ai a M i B . MaHBB « B ...._ i 

The subject of evaporative volatile organic compound emissions from gasoline 

fueled vehicles has recently become a subject of major public and political 

interest in the US and in Europe. 

Carbon canisters containing activated charcoal to adsorb evaporative emissions have been used for many years in the USA, Japan and Australia and more 

recently also in Europe. 

The function of these canisters has only been to adsorb the emissions that 

occur when the car is driven or when the tank breathes as a result of temperature 

variations. The emissions that arise during vehicle refueling, due to the displacement of vapor from the fuel tank by incoming liquid fuel, though, has not yet been 

a subject of uniform corrective measures. 

TWO SYSTEM APPROACHES ARE 

CONSIDERED: •••••••••••>—••— 

1. Since 1974 some counties in California have introduced the ..Service 

Station Vapor Recovery System". 

This operates by using a separate 

pipe to send displaced vapor from the 

vehicle fuel tank back to the underground tank. This approach requires 

not only the reequipment of all service 

station pumps but also all vehicles to 

be equipped with a standardized fuel 

filling orifice. 

2. Equipping the vehicles with an enlarged version of the carbon canister 

described above. With this system 

vapor emissions that arise when 

refueling are adsorbed by the canister. 

Subsequently, the canister is desorbed 

by drawing air through it and into the 

engine. This system is referred to as 

the „On-Board Refueling Control 

System". 

COMPARISON BETWEEN THE TWO SYSTEM APPROACHES: •«•..• . 

The Service Station Vapor Recovery System has the disadvantage of being more 

expensive and less efficient than the On-Board Refueling Control System,see 

comparison below: 

.... 

Efficiency of 

emission capture 

Cost per retained 

1,000 kg of gasoline 

Service Station 

Vapor Recovery 

5 5% 

13,290 DM/t 

On-Board 

Refueling Control 

9 8 % 

770 DM/t 

Source: MWV (The Genmn fctrolcum faduitry Asocialion) 

The on-board system approach primarily has been criticized for. 

1. Being too ..bulky" - a minimum size of 51 canister for a 501 tank is required. 

2. The physical form of the system which makes it difficult to adapt and 

integrate into the automobile. 

3. An increased security risk as a consequence of the inte-gration of the 

enlarged canisters and pipes in the vehicle. 

4. The reduced immediate emission retention due to the fact that the system can 

only be implemented in new cars. 
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THE BLUECHER APPROACH 

a fur aim has been to develop 

an activated charcoal filter for the 

On-Board Refueling Control System 

thatch A: 

4>B: 

4>Cs 

Requires less volume 

Has an improved, more flexible, form design 

Provides a safer system 

THE FOLLOWING CRITERIA 

ARE DECISIVE FOR THE EFFCIENCY OF THE ADSORPTIVE MEDIUM IN THIS APPUCATION: 

1. THE ADSORPTION 

KINETICS OF THE CHOSEN 

ADSORBERS BB ^ B M i 

Basically this is a dynamic process 

where smaller adsorbers should be used 

in order to increase the outer surface 

area and to shorten the distance between the initial and final adsorption. 

Since this normally leads to poorer 

flow characteristics larger particles 

have traditionally been chosen. 

Bluecher designed its filter with 

small spherical adsorbers (0 0.4-0.7 

mm) adhered on a foam matrix, thereby 

optimizing adsorption and flow characteristics. The efficiency of the system also depends on the pore structure 

of the adsorber which has been 

optimized for this application during 

manufacture. 

2. THE ADSORPTION 

CAPACITY •MMBHMMH M 

The utilization capacity (the working 

capacity including the remaining capacity for the next filling) and the 

maximum quantity of gasoline vapor 

to be adsorbed determine the total adsorber capacity needed. Preliminary 

test results have shown that for every 

201 tank content approximately 11 of 

our filter medium is needed. 

3. THE DESORBABIUTY OF 

THE VAPORS aaa^-aaa—!— 

The gasoline vapors are chemically 

not homogenous since they consist of 

chemicals with different molecular 

weights and boiling points. 

In order to adsorb substances with 

low molecular weights like butane, 

smaller sized micropores are needed. 

These, however, arc easily choked by 

larger molecules (e.g. octanes) which 

will not easily desorb and therefore 

reduce the efficiency of the filter. 

Bluecher uses a technique (patent 

pending) where different layers are 

used for the adsorption of the different 

substances. Since the desorption flow 

is in the reversed direction of the adsorption flow the risk of cross-contamination is eliminated. 

4. OTHER ADVANTAGES M ^ 

The Bluecher product can be cut and 

formed into virtually any shape to fit 

the specific requirements of the car 

designer. We are not restricted to a 

typical canister form which in many 

cases is difficult to locate or install. 

Consequently, a location for the filter 

can be chosen with a higher degree of 

safety and lower costs for the car 

manufacturer. 

The primary safety concern with 

the traditional canister has been its 

assumed propensity to catch fire. 

THE FOLLOWING ADVANTAGES VS. CONVENTIONAL ACTIVATED CARBON CANISTERS CAN BE IDENTIFIED: 

• A reduction in volume. 

Preliminary tests have shown that approximately 

1 I filter medium is required for every 20 I tank content. 

• A reduction in weight. 

• An infinite flexibility in design and adapt ability of the filter 

which will enhance the security. 

• An improved safety of the system due to a reduced propensity 

for the filter to become overheated. 

• A substantially lower pressure drop. , 

. The absence of carbon dust which can arise when traditional 

canisters are exposed to vibrations. 

The Bluecher filter reduces the risk of 

the creation of „hot spots", under all 

circumstances, by the predetermined 

and fixed distances between the 

adsorbers. The high air permeability 

of the filter medium also reduces the 

risk of overheating. 

Another advantage ofthe B luecher 

filter is its good airflow characteristic. 

The measured pressure drop is up to 

ten times less than for conventional 

canister filters. Furthermore, the application of adsorbers on a matrix 

guarantee a homogenous utilization of 

the filter volume. 

Finally, the Bluecher filter is a very 

clean filter. The absence of carbon 

dust, even after exposure to vibration, 

should be df considerable interest to 

both the filter and car manufacturers.