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Piezoresistive Pressure Transmitters

Series 21 G

for industrial applications
•t Weighing only 30 grams, the smallest known transmitter with fully welded stainless steel t
t wetted parts
• tHigh EMC protection. Protection class IP65/IP67
• tHighest stability due to special heat treatment and annealing procedures
Series 21G, is the result of a 20 year long development programme for industrial transmitters.
‘G’ stands for ‘Graduate’; this product has received ‘summa cum laude’.... the highest honours.
The standard mPm electrical connector overlaps the body to remind us of ‘mortar board hats’
on graduation day.
The Series 21G combines KELLER’s 30 year long experience of manufacturing industrial pressure transmitters, with all of the newest technological advantages available in the industry today.
This product incorporates the very latest techniques for welding, signal processing and circuitry,
automated compensation and adjustment. Each transmitter is subjected to temperature and
pressure cycles during manufacture. The laser trimming final adjustment gives unrivalled accuracies over a wide temperature range. The result is a cost-effective affordable transmitter that
has a specification better than other similarly priced products, and equal to many very expensive
transmitters.
The body size is determined by the thread selected, 17 mm HEX for G1/8”, 1/8”-27NPT and
7/16”-20 UNF, and 19 mm HEX for the G1/4” thread and 1/4”-18NPT”.
The Series 21G is an OEM product, designed specifically to be built and sold in thousands
only. Alternative customer specific threads, pressure ports, electrical connections and electrical
outputs can be readily accommodated at little or no extra cost. The pressure ranges and temperature compensation can be adapted to suit particular applications. The following guidelines give
an overview of the typical performance of the 4 most commonly used temperature ranges.
Typest
Pressure Rangest

Absolute or sealed gauge
Min: 0...5 bart
Max: 0... 200 bar

Electrical Configurationt
Outputt
Excitationt

2-wiret
4...20 mAt
8...28 Vt

3-wire
0,5...4,5 V ratiometric
5V

Linearity (BFSL)t

typ. 0,25 %FSt

max. 0,5 %FS

typ. 1,0 %FSt
typ. 1,0 %FSt
typ. 1,5 %FSt
typ. 2,0 %FSt

max. 1,5 %FS
max. 1,5 %FS
max. 2,0 %FS
max. 3,0 %FS

Error Bandt
t
t
t

0...50 °Ct t
-40...20 °C / 20...80 °Ct
-20...80 °Ctt
-40...135 °Ct

7/16”-20UNF

1/4”-18NPT

G1/8”

4,5
15

8

12

15

HEXt17

8

max. 38

G1/4”

ø14
øt18,6

12

2
max. 33

2

HEXt17

8

max. 37

HEXt19

8

HEXt19

8

ø 17
12,5

ø 17

ø 17

ø 17
3

≈5

3

7,5

7
7,5

7

16

17

16

4 typical constructions of Series 21 G

Subject to alterations

09/05

KELLER AG für Druckmesstechnikt

St. Gallerstrasse 119t

CH-8404 Winterthurt

Tel. +41 (0)52 - 235 25 25t

Fax +41 (0)52 - 235 25 00

KELLER Ges. für Druckmesstechnik mbHt

Schwarzwaldstrasse 17t

D-79798 Jestettent

Tel. +49 (0)7745 - 9214 - 0t

Fax +49 (0)7745 - 9214 - 60

Companies approved to ISO 9001 / EN 29001

www.keller-druck.com