Activated Carbon Media Study: Block vs Granules

Carbon Filter Life Comparison

Objective A: To compare the filter life efficiency of the granular activated carbon to the block activated carbon and to estimate filter life of the carbon.

Experiment equipment and setup needed: Methyl ethyl ketone (MEK), SS-340-DCH, aluminum pan for chemical containment, flask to measure chemical, gas sensor for indicating breakthrough, velometer, 10 lb granular activated carbon filter, 10 lb block activated carbon filter, scale

Experiment procedure:

– Block carbon filter will be weighed and its initial weight recorded. The block filter will then be placed in the Sentry Air Systems Model 300 unit that will be used in the DCH; no pre-filter will be used.

– The gas sensor will be hooked up and used to monitor breakthrough off the carbon filters (it has been tested and is in working condition). Sensor will be placed on top of the 300 unit.
– The air conditioning should be turned off in the room to prevent vapors to escape into other rooms and to maximize evaporation.
– 500 ml of MEK will be measured and poured into an aluminum pan that has been placed inside the Sentry Air hood. The unit will be powered on at maximum fan speed. The time the unit is turned on marks the beginning of the test and will be recorded.
– The hood setup/alarm will be monitored by an attendant for any indication that filter is saturated. It should take 1.5 to 2L of chemical to saturate the carbon filter. Once 1.5 L is approached, MEK will be added in increments of 20 ml so that it can be more accurately determined how much chemical has been evaporated and absorbed by the carbon filter at breakthrough.
– Breakthrough will occur when the gas sensor alarms. The attendant will note the time this occurs and will record it. The attendant will also record the amount of MEK remaining in aluminum pan.

– Once the gas sensor alarms, the gas sampling pump will be turned on and will absorb the effluent of the filtered air for 5 minutes. After 5 minutes the sorbent tube will be capped and marked and the information will be recorded. The same experimental procedures will be conducted for the granular carbon.

Results and Analysis: A few seconds after placing the block carbon in the 340 DCH, turning it on and pouring the MEK into the containment pan, the gas sensor alarm went off. Wafting the air coming from the filter produced the distinct smell of MEK. It was initially thought that this was an anomaly and so the room air was cleared out and a new block carbon replaced the old block carbon inside the Sentry Air Ductless Containment Hood. The test was repeated with the same results. This test was then repeated a third time with the same results.

After the room was cleared out again, the block filter was replaced with the filter containing activated carbon granules. The 300 Mounted Sentry was turned on again and the alarm didn’t sound. The unit was left on for a few hours and the alarm never sounded. From our modified test, the granulated carbon was seen to efficiently remove MEK and other vapors.

Conclusion: It is very apparent from the short tests that were performed that the granulated carbon greatly outperformed the block activated carbon. The block activated carbon really didn’t help much, if at all, in fume removal.

Moreover, the efficiency of the granulated activated carbon on filtering MEK vapors was later tested in a Sentry Air Ductless hood. It was shown that the MEK was filtered at an efficiency of over 95%. To see complete results of this test, you can view the report that contains all the data on our website.