# How to select primary element Differential Pressure flow measurement? **URL:** \ **Category:** Pressure Measurement\ **Created:** [March 8, 2016, 5:06am UTC](https://forumautomation.com/t/how-to-select-primary-element-differential-pressure-flow-measurement/837 "2016-03-08T05:06:19Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![denizen](https://forumautomation.com/letter_avatar_proxy/v4/letter/d/848f3c/32.png) [@denizen](https://forumautomation.com/u/denizen)\ **Post date:** [March 8, 2016, 5:06am UTC](https://forumautomation.com/t/how-to-select-primary-element-differential-pressure-flow-measurement/837/1 "2016-03-08T05:06:19Z")
Advantages and Limitations of different types primary element (Differential Pressure Flow Measurement) **Square Edge Concentric Orifice Plate** Recommended Service - Clean Liquid,Gases,Steam Advantages - Easy to install Low cost Easy to replace Limitation - Relaxation piping requirement High head loss Accuracy affected by installation and orifice condition **Conical / Quadrant edge concentric orifice plate** Recommended Service - Viscous Liquid Advantages - Easy to install Low cost Easy to replace Limitation - Relaxation piping requirement High head loss Accuracy affected by installation and orifice condition **Eccentric / Segemental Orifice plate** Recommended Service - Liquids and gases containing secondary fluid phases Advantages - Easy to install Low cost Easy to replace Limitation - Relaxation piping requirement High head loss Accuracy affected by installation and orifice condition Higher uncertainties of discharge coefficient data. **Integral Orifice** Recommended Service - Clean Liquids,Gases,Steam Advantages - Easy to install No lead lines Low cost Limitations - Relaxation piping requirements Proprietary design requires calibration High head loss More prone to clogging than standard orifice plate **Venturi / Flowtube** Recommended Service - Clean and dirty liquids,Gases,Steam,Slurries Advantages - Low head loss 2 to 9 times less relaxation piping than orifice Higher flow capacity than orifice for same differential pressure Accuracy less affected by wear and installation condition than orifice Limitation - High Initial Cost **Nozzle** Recommended Service - Clean Liquids,Gases,Steam Advantages - Higher Flow capacity than orifice for the same differential pressure Accuracy less affected by wear and installation condition than orifice Good for high temperature and high velocity application Mass transfer standard for gases Limitation - Harder to replace than orifice High head loss **Segmental Wedge** Recommended Service -Dirty Liquid,Gases,Steam,Slurries,Viscous Liquid Advantages - No lead lines Minimal clogging potential 40% less head loss than orifice Minimal relaxation piping Limitation - Proprietary design needs calibration High initial cost Requires remote seal differential pressure transmitter,harder to zero **Venturi Cone** Recommended Service - Clean and dirty liquids,gases,Steam,Viscous liquids Advantages - Minimal relaxation piping Low flow capability Limitation - Proprietary design