INSTRUCTION MANUAL AND REPLACEMENT PARTS
DESCRIPTION
T20 and T21 units are simple, reliable
designed for top mounting to tanks or vessels. T20 units
utilize a single switch mechanism and float. T21 tandem
units utilize two switch mechanisms and two separate
floats when widely spaced actuating levels are required.
T20 and T21 tandem models are available for any type of
open or closed vessel with either threaded or flanged type
mounting and actuating depths up to 1219 mm (48 inches)
OPERATING PRINCIPLE
①
A permanent magnet
is attached to a pivoted switch
②
actuator
. As the
float/ displacer
uid level, it raises the attraction sleeve
the magnet, which then snaps against the non-magnetic
⑤
enclosing tube
, actuating the switch. The enclosing tube
provides a static pressure boundary between the switch
mechanism and the process. On a falling level, an inconel
spring retracts the magnet, deactivating the switch.
②
pivot
⑤
return spring
④
①
③
rising level
UNPACKING
Unpack the instrument
carefully. Inspect all units for dam-
age. Report any concealed damage to carrier within 24
hours. Check the contents of the packing slip and purchase
order. Check and record the serial number for future refer-
ence when ordering parts.
®
float switches
③
rises following the
liq-
④
into the
field of
falling level
T20 & T21
Top mounting
Liquid level switches
AGENCY APPROVALS
Agency
Approval
ATEX
II 2G EEx d II C T6, explosion proof
II 1G EEx ia II C T6, intrinsically safe
CENELEC
EEx d
II C T6, explosion proof
➀
CCE
R1 (1) 136/MI/433, explosion proof
FM
Class
I, Div. 1,
Groups C & D
Class
II, Div. 1,
Groups E, F & G, Type NEMA 7/9
➁
FM/CSA
Non-Hazardous area
Explosion proof area –
Groups B, C, D, E, F & G Type NEMA 4X/7/9
➁
Explosion proof area
SAA
LRS
Lloyds Register of Shipment (marine applications)
GOST/
Russian Authorisation Standards
➁
GOSGORTECHNADZOR
Other approvals are available, consult factory for more details
➀ For CCE approved units, use the
numbers.
➁ Consult factory for proper model numbers.
ATEX explosion proof model