Yokogawa Pressure Transmitters Differential Pressure

Differential Pressure (DP) is defined as the difference between two pressures. Differential Pressure Transmitters use a reference point called the low-side pressure and compare it to the high-side pressure. Ports in the instrument are marked high-side and low-side. The DP reading can be either negative or positive depending on whether the low-side or high-side is the larger value. A DP transmitter can be used as a gauge pressure transmitter if the low-side is left open to the atmosphere. Yokogawa Differential Pressure Transmitters use Digital DPharp sensor technology to get accurate readings to your control unit fast.

  • EJA110E

    EJA110E thumbnailTraditional-mount Differential Pressure Transmitter based on the EJA-E Series.


  • EJX110A

    EJX110A thumbnailTraditional-mount Differential Pressure Transmitter based on the EJX-A Series.


  • EJA118E

    EJA118E thumbnailDifferential Pressure Transmitter with Remote Diaphragm Seals based on the EJA-E Series.


  • EJX118A

    EJX118A thumbnailDifferential Pressure Transmitter with Remote Diaphragm Seals based on the EJX-A Series.


  • EJA130E

    EJA130E thumbnailTraditional-mount High Static Differential Pressure Transmitter based on the EJA-E Series.


  • EJX130A

    EJX130A thumbnailTraditional-mount High Static Differential Pressure Transmitter based on the EJX-A Series.


  • EJXC40A

    EJXC40A thumbnailDigital Remote Sensor (DRS) Transmitter connects two pressure sensors, master (high pressure side) and slave (low pressure side) in a remote location, with DRS dedicated communication cable to measure differential pressure.


  • EJXC80A, EJAC80E (Diaphragm Seal)

    EJXC80A, EJAC80E (Diaphragm Seal) thumbnailDiaphragm Seal System consists of gauge pressure or differential pressure transmitter with one or two diaphragm seal.


  • EJXC80A, EJAC80E (Direct Mounted)

    EJXC80A, EJAC80E (Direct Mounted) thumbnailDirect Mounted Diaphragm Seal System consists of gauge pressure or differential pressure transmitter with single direct mount diaphragm seal.


  • EJXC50A, EJAC50E

    EJXC50A, EJAC50E thumbnailDirect Mounted Diaphragm Seal System consists of gauge pressure or differential pressure transmitter with single direct mount diaphragm seal.


  • P10

    P10 thumbnailP10 series can be used to measure not only differential pressure but also flow rate, liquid level, density and other process variables.

Introduction

Level transmitter configuration can be very time consuming. Calculations required to determine proper range values for traditional transmitters can become complex due to the physical layout of an application.

With maintenance shops getting smaller, finding equipment that allows us to do more with fens becomes a priority. DPharp transmitters with advanced software functionality can eliminate these complex calculations.

Which Series is Right for You?

EJA-E SeriesEJX-A Series
EJA-E SeriesEJX-A Series
Accuracy
± 0.025%
± 0.040%
± 0.055%
± 0.065%
Stability
± 0.1% of URL per 10 years
± 0.1% of URL per 7 years
± 0.1% of URL per 5 years
Response Time
90 msec
300 msec
Safety
FMEDA Report
IEC 61508 Certified (SIL 2)
Multi-sensing
Differential Pressure
Static Pressure

Application

Using typical smart or conventional products, all the following must be considered:

The specific gravity of the processSGP
Precise location of 0% and 100%

Specific Gravity of the capillary fill fluid
(or sealing fluid used in impulse piping)

SGFF
Exact orientation oi the transmitter to the vesselH2
Vertical distance between the process conn.H1

Depending on the application, the vessel may be open (referencing atmosphere) or closed (under a blanket pressure).

Elevation is typically used when the vessel is closed. To reference the blanket pressure, a low side remote seal may be used (or a wet leg). The capillary on remote seal creates a negative force on the transmitter equal to the vertical height times the specific gravity of the fill fluid.

Elevation = (H1 + H2) x SGFF

Suppression is a positive pressure created on the high-pressure side of the transmitter typically due to the transmitter being positioned below the 0% process connection. Suppression is present in both open arid closed vessels. Suppression is equal to the vertical distance between the 0% process connection and the transmitter times the Specific Gravity of the fill livid.

Suppression = H2 x SGFF

Span is the vertical distance between the process connections times the process medium’s Specific Gravity.

Span = H1 x SGP

Figure 1: Closed Tank
Figure 1: Closed Tank

Now that you have the ElevationSuppression, and Span, the calibration values can be calculated for the 0% (Empty) arid the 100% (Full).

Cal Value (0%) = Suppression – Elevation

Cal Value (100%) = (Suppression + Span) – Elevation

Example: (using figure 1)

SGP0.9H210 inches
SGFF0.8H120 inches

Cal Value 0%) = Suppression – Elevation
Cal Value (0%) = (H2 x SGFF) – (H1 + H2 x SGFF)
Cal Value (0%) = (10 x 0.8) – (20 + 10) x 0.8
Cal Value (0%) = 8 – 24
Cal Value 0%) = -16 inH2O

Cal Value (100%) = (Suppression + Span) – Elevation
Cal Value (100%) = ((H2 x SGFF) + (H1 x SGP)) – (H1 + H2) x SGFF
Cal Value (100%) = ((10 x 0.8) + (20 x 0.9)) – (20 + 10) x 0.8
Cal Value (100%) = (8 + 18) – 24
Cal Value (100%) = +2 inH2O

Therefore, Calibrated Range would be:

-16 inH2O +2 inH2O
0%100%
EmptyFull