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Bulletin: 2013-004

Date: 04-15-2013

Category: 1

Program affected: PIPE-FLO Professional 12

Build numbers affected: 12.0.19520

Approved by: JB

Background

Centrifugal Pump Operation can be specified as Variable Speed at a Set Flow. Under this operation, PIPE-FLO 12 will calculate the pump speed and resultant Total Head required to meet the Set Flow under the current lineup settings. In the case where this speed is outside of the speed range set by the user or manufacturer, PIPE-FLO 12 should issue a message stating that: "The speed cannot be adjusted to the calculated operating point." This is a Level 2 message and an indicator that the results may be in question. Currently, this warning is not being issued and the Total Head and dP reported by the pump are not based on lineup conditions and are not valid results. If this occurs, the user will see that the speed is set to the closest limit of the range, and that the Pump dP does not match the difference between the Pump Suction and Discharge Pressures.

Condition

  1. The user has a Centrifugal Pump with a Catalog or User Entered curve, set to Variable Speed Operation.
  2. The calculated speed is outside of the Minimum and Maximum Speed range specified by the user or manufacturer. If no range is entered, it is limited to the Design Speed.
  3. PIPE-FLO 12 does not currently issue a "speed cannot be adjusted to the calculated operating point" warning for this condition.
  4. Speed will be adjusted to the closest limit of the range. Total Head and dP reported at the pump are not valid and will not match the Pump Suction and Discharge Pressures.

Solution

  1. User should verify that the reported Pump dP matches the difference between Pump Suction and Discharge Pressures when the calculated speed is at the limit.
  2. In the case of a User Entered Curve, the user can adjust the Minimum and Maximum Speeds.

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