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EGE-Elektronik Spezial-Sensoren GmbH • http://www.ege-elektronik.com

E11011 1.05

Flow Sensors

Technique and application

Installation in rising pipe

T-piece

Gasket

AFM ...

Gasket

AFM ...

Compact-

model

Flow sensor

NPT threads

NPT threads can be provided as an alternative for all types

which have a G1/2 or a G3/4 thread. NPT threads are coni-

cal and must be screwed into an equally conical counter-

part. Two types of NPT threads must be distinguished:

NPT thread to ANSI B 1.20.1

This thread does not ensure a good seal by itself and

requires the use of a sealing medium, e.g. Teflon tape. It is

not possible to use flat gaskets with this type of thread.

NPT thread to ANSI B 1.20.3

This thread does ensure a good seal by itself and requires

no further sealing medium. When this type of thread is

used, special attention must be paid to the kind of metal

used for both parts of the thread, so as to avoid metal seiz-

ing when the parts are screwed tight.

Media

The sensitivity of thermodynamic flow monitors depends

on the thermal characteristics of a medium. The detection

range of a standard sensor for oil, for example, is three

times as great than for water and for air is approx. 30 times

greater than for water due to the reduced heat conductivi-

ty. Unless stated otherwise, the technical sensor data are

specified for water.

Flange

Standardised pipe connections are required particularly in

the chemical, pharmaceutical and foodstuff industries.

Sensors for use in these areas are supplied with flange

connections per DIN or ASME. Sensor and flange form a

corrosion-proof connection using laser or inert gas shield-

ed arc welding.

Food-approved screw connections

For hygienic reasons the food and pharmaceutical indus-

tries place special demands on the mechanical and elec-

tronic characteristics of sensors.

Flow monitors with food-approved connections, e. g. Tri-

clamp or dairy pipe connections (DIN 11851) comply with

the 3-A sanitary standard 28-03. Due to the temperature

changes involved, the usual cleaning cycles CIP and SIP

place a particular demand on sensor electronics. There-

fore, special protective measures are taken. Sensor mate-

rials for these applications is mainly the special steel AISI

316 L. Customer-specific connections, e. g. GEA-Varivent

or APV flanges are available, as are other special metallic

materials.

Extra long sensors

Flow monitor sensors are available in screw lengths of 25

mm to 300 mm. Sensors for use in explosive environments

are made of two components if longer than 110 mm and

joined corrosion-proof through laser welding. The sensor

length should be selected such that the measuring tip is

within an area of stable flow characteristics.

Main applications are:

– detection of small flow velocities in large section pipes

– mounting of the sensor with a standard flange

– use of extra long welding sleeves if the piping is

surrounded by a supplementary insulation.

For these cases, special shapes can be supplied up to a

maximum length of 300 mm. Immersion depth "L" is deter-

mined by the distance between the sealing face and the

sensor tip. Stainless steel 1.4571 (AISI-316 Ti) is used for

this special model.

Standard lengths which can be supplied are: L = 80 and

120 mm; in the Ex-area 80, 110 and 140 mm.

Inline

Inline sensors are inserted directly into the line of a pipe.

This design does not feature any measuring pins protrud-

ing into the flow. EGE inline sensors SD of series 500 are

suitable for flow volumes from 0.5 ml/min to 6 l/min; EGE

inline compact devices can also monitor flows up to 30 l/

min. These sensors excel through smooth measuring

pipes, low pressure loss and fast response to flow chang-

es. A multitude of connection options are available.

Ø 17

20 15

Ø 7,3

Long sensor

1 2 3 4 5 6 7 8 9 10 ... 83 84

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