Selection constraints captures additional requirements for the Selector to base it's search. The image below shows the Selection Constraints twistie in the Operating Conditions tab of the Conditions of Service Page.
The user has the ability to define performance adjustments for centrifugal pumps, as show below. The display of this new section is controlled by a privilege, so that it can be entered only for a specific subset of users.
Click on the fields below for more information.
Centrifugal Pump Constraints:
This field allows the user to specify a margin to be included when evaluating the NPSH required. The equation [NPSHr + NPSHmargin <= NPSHa] must be satisfied before a selection is accepted. Selections with inadequate NPSHr will be displayed as a Near miss along with the reason for non-conformance.
This field allows the user to specify a minimum percent requirement they have in terms of a head rise to shutoff. Any selections not in conformance with the specified value will be displayed as a Near miss along with the reason for non-conformance.
"Using discharge orifice, where permitted" allows the user to request the use of a discharge orifice to enable the requested head rise to shutoff.
This field allows the user to specify a maximum percent requirement they have in terms of a head rise to shutoff. Any selections not in conformance with the specified value will be displayed as a Near miss along with the reason for non-conformance.
This field allows the user to specify a maximum shutoff head. Should the user defined maximum shutoff head exceeds the rated shutoff head, a near miss will be returned per the equation below.
headShutoffMaxUser >= headShutoffRated
Stable head/flow curve required?
This field allows the user to specify whether selections shall have a stable (continuously falling, non-drooping) head curve. Any selections not in conformance will be displayed as a Near miss along with the reason for non-conformance.
Maximum suction specific speed
If the conditions of service requirements limit the suction specific speed, enter the maximum allowable index value. The selector will check this value against the calculated suction specific speed value for each selection result. If the calculated value exceeds the maximum value a near miss will result.
If the conditions of service design requirements limit the impeller specific speed, enter the maximum allowable index value in this field. The selector will check this value against the calculated specific speed value for each selection result. If the calculated value exceeds the maximum value a near miss will result.
Centrifugal Pump Performance Adjustments
If it is desirable to adjust the flow performance, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
Flow adjustment factor, efficiency only (shift BEP)
If it is desirable to adjust the flow performance for efficiency only (shift BEP), enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
Flow adjustment factor, end-of-curve only
If it is desirable to adjust the flow performance at the end-of-curve only, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
Head adjustment factor at all flows
If it is desirable to adjust the head performance at all flows, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
Head adjustment factor at rated flow, shutoff unadjusted
If it is desirable to adjust the head performance at rated flow (shutoff unadjusted), enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
If it is desirable to adjust the efficiency performance, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
NPSH required adjustment factor
If it is desirable to adjust the NPSH required performance, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
If it is desirable to adjust the MCSF required performance, enter the factor value here. This factor will combine with any factor adjustment defined by the manufacture. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
If it is desirable to adjust the power performance, enter the value here. This value will define the efficiency adjustment factor. The results will display on the Performance Data section on the General Pump Data twistie on Additional Data tab section of the Performance Datasheet Page.
If it is desirable to adjust the torque performance, enter the value here. This value will define the efficiency adjustment factor. The results will display on the Mechanical Limit section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
User applied performance adjustment comments
If it is desirable to make adjustments, you can also add a corresponding comment. The text will display on the Performance Data section on the General Pump Data twistie on Additional Data tab of the Performance Datasheet Page.
Specifications:
Hydraulic selection specification
This field allows the user to have all selections made in accordance with industry standard selection specifications, such as API 610 or NFPA. The options in this list are definable by the supplier and rules can be defined that dictate what specifications are shown basis the selection of other drop-down lists. Selection of a specification will apply all the selection criteria for that specification during the pump selection process, such as minimum head rise to shutoff and preferred operating regions around the best efficiency point. Additionally when API 610/ISO 13709 hydraulic specification is selected, additional criteria can be defined by clicking the "More >>" link. Any pump not in accordance with the specification will be displayed as a Near miss along with the reasons for non-conformance.
Examples are API, ANSI, DIN and ISO. The list of specifications is defined by the supplier and the user's selection will only display product lines that are designed to meet that specification on the Product Lines page.
General Constraints:
This field is designed to help the user who may not be familiar with the portfolio of products or their available materials. The selection will eliminate products from the Product Lines page that cannot be supplied in that material. Unless otherwise specified, the user is responsible for specifying a material suitable for Conditions of Service (liquid, temperature etc.).