Delta p (Δp)

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Delta (Δ) is the fourth let­ter of the Greek al­pha­bet, is used as a math­e­mat­i­cal sym­bol and de­scribes the dif­fer­ence of any vari­able quantity. 

Ex­am­ples of quan­ti­ties are:

  • Length
  • Mass
  • Time
  • Cur­rent

P is the for­mu­la sym­bol for the phys­i­cal pres­sure. Pres­sure in­di­cates the force ex­ert­ed by a body on a sur­face. Pres­sure is ex­pressed in pas­cals (Pa). When these two pieces of in­for­ma­tion are com­bined, it is un­der­stood that delta p (Δp) stands for pres­sure difference.

Use of delta p (∆p)

Delta p (∆p) thus de­scribes the pres­sure dif­fer­ence be­tween two mea­sured val­ues. These val­ues can be mea­sured at dif­fer­ent times or at dif­fer­ent lo­ca­tions in a sys­tem. Three sit­u­a­tions can be recorded:

  • The pres­sure has not changed, it has re­mained the same.
  • The first val­ue is small­er than the sec­ond val­ue — pres­sure increase 
  • The first val­ue is greater than the sec­ond val­ue — pres­sure drop. 

Calculation of delta p (∆p)

∆p = p1 — p2

Practical examples of delta p (∆p)

Pres­sure dif­fer­ences can be mea­sured in many ar­eas. Typ­i­cal ex­am­ples are the pres­sure drop in a pip­ing sys­tem — for ex­am­ple be­fore and af­ter a tool, a heat ex­chang­er, a pump or a fil­ter. A small pres­sure drop in these ex­am­ples is due to wall fric­tion in the systems.

Unintended pressure differences

Delta p (∆p) is an im­por­tant mea­sure­ment of the qual­i­ty of pres­sur­ized sys­tems. Un­in­tend­ed changes in the pres­sure struc­ture quick­ly have a neg­a­tive im­pact on the func­tions in the sys­tem and should be no­ticed and cor­rect­ed as soon as pos­si­ble. For quick ver­i­fi­ca­tion of pres­sure dif­fer­ences, da­ta log­gers can be used to record changes in the cir­cuit and pro­vide con­clu­sions about the problem.

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