How to calculate remote seal transmitter temperature error?

Remote seal pressure transmitters benefits

The following benefits of remote seal pressure transmitters make them perfect for various process industries:

The pressure transmitter and the medium are separated to avoid dangerous consequences.

The transmitters are available in a vast variety and customized designs.

They are designed to withstand rigors of harsh working environments.

Remote seal transmitters offered by Hiltech are FDA grade. These transmitters are ideal for the food and pharmaceutical applications.

Remote seal differential pressure transmitter applications

Remote seal pressure transmitters are ideal to use when:

The temperature of the process medium is higher than the maximum specified limits of the pressure transmitter.

The medium has solid particles, or has high viscous consistency. In both cases, there are chances of measuring chambers of the pressure transmitter getting blocked.

The medium may freeze in the pulse line, or the measuring chamber.

The medium is heterogeneous, or has fibrous texture.

The medium has a tendency to crystallize or polymerize during swings in the process or ambient temperature.

The medium is corrosive and demands diaphragm seals.

The process demands cleaning of the measuring point. For example – In a batch process, remote seal transmitters are used to avoid contamination between batches.

The process demands sanitary seals to avoid dead volume and cavities. For example –food, beverage, and pharmaceutical applications.

The process application is conducted in a limited space.

Industries using pressure measurement remote seals

The following are some of the industries that use pressure measurement remote seals.

Hydrocarbon Processing

Chemical

Food

Pharmaceutical

Beverages

Calculate temperature error for diaphragm seal level transmitter

The following formula is used to calculate the temperature error of the remote seal:

dp = (tRS – tCal). fRS + (tCap – tCal).

lCap. fCap + (tTR – tCal). fPF

where

Calculation example for remote seal temperature error

Existing conditions:

dp – Additional temperature error (inH2O)

tRS – temperature on the distal seal diaphragm (usually corresponds to medium temperature)

tCal – reference (calibration) temperature of 68°F

fRS – temperature error of remote seal

tCap – ambient temperature of the capillary

ICap – capillary extension length (give error every 3 feet)

fCap – Capillary temperature error

tTR – ambient temperature of the transmitter

fPF – temperature error of oil fill in transmitter process flange

Remote Sealed DP Transmitter, fRS = 0.054 inH2O / 25°F

Capillary ICap = 2 x 15 feet

Capillary on both sides, fCap = 0.042 inH2O / 25°F / 3 ft

Filled with Silicone Oil DC 200-10, fPF = 0.042 inH2O / 25°F

Media temperature 212°F, tRS = 212°F

Capillary temperature 122°F, tCap = 122°F

Temperature on transmitter 122°F, tTR = 122°F

Additional temperature error for remote seal: dp

Calculation:

dp = (212°F – 68°F). 0.077 in water column / 25°F+ (122°F – 68°F). 15 feet 2.0.042 inches of water

Column / 25°F / 3ft+ (122°F – 68°F). 0.042" water column / 25°F

dp = 0.444 inches of water + 0.907 inches of water + 0.091 inches of water

result:

dp = 1.442 inH2O (equivalent to 3.605% of set span)

Notice:

The temperature error determined above applies only to the error caused by connecting the remote seal.

Transmission responses from individual transmitters are not included in consideration. It must be calculated separately, and the resulting error is added to the above by connecting the error determined by the remote seal. When using remote seals, it is always based on physics resulting in measurement errors.

Temperature error when the diaphragm seal is connected to a pressure, absolute pressure or level transmitter, and when one side is connected to a differential pressure transmitter.

temperature error

Remark:

Filled with Silicone Oil DC 200-10, fPF = 0.042 inH2O / 25°F

Media temperature 212°F, tRS = 212°F

Capillary temperature 122°F, tCap = 122°F

Temperature on transmitter 122°F, tTR = 122°F

Additional temperature error for remote seal: dp

These values apply to filling fluids: silicone oil DC 200, high temperature oil, halocarbon oil and Neobee M20.

This value applies to stainless steel as diaphragm material.

Temperature Error vs. Diaphragm Material

The errors listed in the tables on pages 2/140 and 2/141 refer to the use of stainless steel as the diaphragm material. If other materials are used, then

The listed values will change the amount shown in the table below.