DATE: May 06, 2005
TO: Rick Baker, Chief
FROM: Bob Baker, Captain
SUBJECT: Positive Pressure Fans
The positive pressure fans we carry, on the engines, are extremely beneficial tools. They are
helpful in many ways, but as we have discussed in the past, we need to examine the process of
selecting these fans. The start-up procedures are considerably different with the three fans we
presently use. As you know, this can inhibit the process of smoke removal.
CAPACITY OF FANS
The fans we carry on the engines are sufficient to handle the jobs we use them for at this time.
The cfm (cubic feet per minute) is sufficient to displace the smoke from most of the structure
fires we extinguish. However, the capacity of fans is not the same.
Engine 811 has a “Ram” fan with a capacity of 15,500 cfm.
Engine 812 has a “Tempest” fan with a capacity of 9,500 cfm
Engine 814 has a “Tempest” fan with a capacity of 9,500 cfm.
STYLES OF FANS
We have used the belt drive type fans for several years.
The belt drive fans are bigger (twenty-one inches).
They produce more noise.
They have more parts that are moving.
They take up more room in the compartments or on the tailboard.
The “Ram” fan is new, and it is a direct drive type.
The direct drive fan is smaller (eighteen inches).
It creates less noise and produces more cfm.
Since it is direct drive, it has less moving parts.
The overall size of the fan is much smaller.
As you can see, the fans have a large difference in capacity and size. The standardization of
equipment should influence the types of fans purchased.
OPERATION OF THE FANS
All three fans operate the same way, but they have some differences with regards to starting.
Rick Baker, Chief
May 06, 2005
The fan on Engine 812 has the pump bubble system to prime the carburetor. The throttle
switch is located on the left side of the engine (motor). This fan also has a fuel shut-off
that is located under the fuel tank.
The fan on Engine 814 has a choke lever. The throttle switch is located on the front of the
engine. This fan does not have a fuel shut-off.
The fan on Engine 811 is the new “Ram” fan. The choke lever is located on the left side
of the engine under the fuel tank. The throttle switch is located directly under the choke
lever. The fuel shut-off is below the choke switch.
The three fans vary in age; however, the costs have not risen dramatically.
The fan on Engine 814 costs $1,795.00.
The fan on Engine 812 costs $1,875.00.
The fan on Engine 811 costs $1,795.00.
Belt Drive Belt Drive Direct Drive
Type of Fan (Engine 812) (Engine 814) (Engine 811)
Size of Fan 21 inches 21 inches 18 inches
CFM's 9,500 9,500 15,500
Cost $1,875.00 $1,795.00 $1,850.00
Gas Shut-off Yes No Yes
Engine Choke No Yes Yes
CONCLUSION AND RECOMMENDATIONS
The three fans are extremely beneficial pieces of equipment, but they have several differences in
regards to operational procedures. As stated in the previous sections, the operation of these three
pieces of equipment is extremely different.
I recommend for future purchases we carefully select fans that are operationally equivalent. The
placement of the choke, throttle, and fuel shut-off is essential in regards to safety, speed of use,
and simplicity. Standardization of the fans will facilitate a faster and easier operation. As you
know, emergency scenes can be extremely hectic. The standardization of equipment will reduce
the chances of mistakes occurring.
Please review the comparison chart above for a summary of the major features of each fan. Feel
free to contact me anytime with questions or comments that you may have.