Blower Model Selection guide

  If you already know your air requirements, simply select the pressure and flow from the DB Model Performance Chart. (See Below) The intersection will be the horsepower color and the performance letter.

Model examples are DB-5M, DB-7E AND DB-10B.

A typical blower system will have plumbing to deliver the air to the required location and orifices at the end to achieve the desired flow and pressure. 

If you don’t know the air flow of your system, we have charts to help you determine that. 

If you don’t know what orifices and pressure is needed, contact the design engineer for your air system, then return here to select your blower.

  Start with the air pressure required at the end of the system. 

DB blowers deliver pressures between 30” and 90” of water column. 

Next determine your total flow by adding together each orifice size flow rate at pressure. For drying and blow-off applications, it will typically be air knife slots and/or round hole nozzles.

Use the CFM Output for Air Knife Slots Chart and the CFM Output for Round Nozzles Chart (See Below) to determine the system flow rate at the required pressure.

  Example:

65” H2O PRESSURE

3 Nozzles, 1/2", 44 CFM each X 3 = 132 CFM 

2 Air Knifes, 12” long by .060” slot, 161 CFM per foot X 2 = 322 CFM

Total = 454 CFM

Suitable Blower Model

DB-7E 72” H2O PRESSURE @ 500 CFM

The plumbing size and length used to deliver the blower air to the orifices will affect the system performance.

Locate the blower close to the delivery point. Large, straight, smooth wall plumbing works best. Elbows and flex hose will have more pressure drop. When necessary, use long radius elbows and keep flex hose to a minimum and straight as possible. 

Use the Pressure Drop in Pipe Chart (See Below) to determine the pipe size for the allowable pressure drop. Multiply the selected rate per foot times 5 for a 45° short radius elbow and times 10 for a 90° short radius elbow. A short radius elbow has a centerline radius equal to the diameter. The longer the radius, the less the pressure drops.  

Example:

65” H2O PRESSURE @ 500 CFM

3” Straight Pipe:   .54”/ft X 20 feet long =  11” H2O Pressure Drop

4” Straight Pipe:   .14”/ft X 20 feet long =     3” H2O Pressure Drop

5” Straight Pipe:   .04”/ft X 20 feet long =     1” H2O Pressure Drop

4” 45° Short Radius Elbow:  .14”/ft X 5 =     .7” H2O Pressure Drop

4” 90° Short Radius Elbow: .14”/ft X 10 = 1.4” H2O Pressure Drop

Suitable Blower Model & Pipe Size

DB-7E 72” H2O PRESSURE @ 500 CFM & 4” Pipe

Use 4” Pipe with model DB-7E for 69” H2O PRESSURE @ 500CFM after pressure drop.

Add quantity (1) 45° Short Radius Elbow and (2) 90° Short Radius Elbow for 

65” H2O PRESSURE @ 500 CFM after the additional pressure drop.

Altitude Adjustment

 Altitude influences the blower pressure.

Sea level is the base line. Air pressure will decrease with increasing altitude.

Use the Altitude Adjustment Chart (See Below) to determine what factor to apply to your blower pressure.

Example:

65” H2O PRESSURE @ 500 CFM in Denver Colorado

For 5,300 ft elevation use a 1.20 correction factor which requires a blower that produces 

78” H2O pressure at sea level.

Suitable Blower Model

DB-10C 81” H2O PRESSURE @ 500 CFM

Temperature Adjustment

The temperature of the air influences the blower pressure as well.

70 °Fahrenheit is the base line. Cold air pressure will increase, and hot air pressure will decrease about 1.25” H2O with each 10 °F incremental change in temperature. 

Use the Temperature Adjustment Chart (See Below) to determine what factor to apply to your blower pressure.

Example:

65” H2O PRESSURE @ 500 CFM in Pheonix Arizona

For 110 °F ambient air, use a 1.08 correction factor which requires a blower that produces 70” H2O pressure at 70 °F.

Suitable Blower Model

DB-7E 72” H2O PRESSURE @ 500 CFM