Fan Law Calculator

Fan Specification

	Current	Proposed
*Flow Rate (cfm)
Fan Speed (rpm)
Fan Static Pressure (inWG)
**Fan Power (hp)

*required field
**required for cost calculations

Annual Cost Estimator

Average annual energy rate ($/kWh)

Average annual demand rate ($/kW)

Annual operating hours

Motor Efficiency (%)

Current annual operating cost ($)

Annual operating cost of proposed system ($)

The proposed flow rate will ($) when compared to the current flow rate.

 

Fan Law Calculator Instructions

The fan law calculator is designed to accept inputs of the current fan specification and a proposed flow rate and use the fan laws to calculate the specification for the proposed system. The calculator can be used to show the large changes in horsepower resulting from small changes in fan flow rates.

Inputs

• Flow rate - the volumetric flow rate of the fan in the current condition and a proposed condition. The proposed condition may be higher or lower than the current condition.
• *Fan speed - the current speed of the fan that produces the current flow rate.
• *Fan static pressure - the current static pressure produced by the fan at the current flow rate.
• *Fan power - the current measured horsepower of the fan at the current flow rate
  *denotes optional input

Outputs

• Fan speed - if a current fan speed is specified, the calculator will calculate the fan speed required to produce the proposed flow rate.
• Fan static pressure - if a current fan static pressure is supplied, the calculator will calculate the fan static pressure required to produce the proposed flow rate.
• Fan power - if a current fan horsepower is supplied, the calculator will calculate the fan horsepower required to produce the proposed flow rate.

Annual Cost Estimator Instructions

The annual cost estimator uses inputs of utility costs and operating hours, in conjunction with the fan horsepower at the two seperate operating points, to estimate the annual cost of operating the fan at the different operating points. Horsepower data from the fan law calculator is required to estimate operational costs.

Inputs

• Average annual energy rate - the average annual marginal cost of energy per kWh. For a less accurate estimate, you may use an aggregate energy rate.
• Average annual demand rate - the average annual marginal cost of demand per kW. Enter zero (0) if using aggregate energy rate.
• Annual operating hours - the number of hours the fan operates annually.

Outputs

• Current annual operating cost - the estimated cost of operating the fan in the current condition.
• Annual operating cost of proposed system - the estimated cost of operating the fan in the proposed condition.

Contact the Arkansas Industrial Energy Clearinghouse if you need assistance with this calculator.