Endress+Hauser Deltabar PMD75B - Product Description; Product Design Overview; Measuring Cell Details; Flow Measurement Principles

Deltabar PMD75B PROFINET with Ethernet-APL Product description
Endress+Hauser 11
3 Product description
3.1 Product design
3.1.1 Measuring cell for differential pressure with metallic
membrane
+ -
p
1
p
1
1
2
3
4
5
4
p
2
p
2
A0043083
1 Measuring element
2 Middle diaphragm
3 Fill fluid
4 Membrane
5 Seal
p
1
Pressure 1
p
2
Pressure 2
The membrane is deflected on both sides by the pressures that are applied. A fill fluid
transfers the pressure to a side of the measuring element where a resistance bridge is
located (semiconductor technology). The change in the bridge output voltage, which
depends on the differential pressure, is measured and processed further.
3.1.2 Flow measurement
Flow measurement with Deltabar and differential pressure sensor:
ESC
-
+ E
ESC
-
+ E
Q Q
Q ~ Q ~
∆ ∆p p
+ +
– –
p
1
p
1
p
2
p
2
A B
A0038340
A Orifice plate
B Pitot tube
Q Flow
Δp Differential pressure, Δp = p
1
– p
2
Advantages:
• A specific unit is defined
• With the Low flow cut off parameter, positive zero return can be configured in the lower
measuring range.