INSTRUCTION MANUAL AND REPLACEMENT PARTS
AGENCY APPROVALS
DESCRIPTION
T20 and T21 units are simple, reliable float switches
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
A permanent magnet ① is attached to a pivoted switch
actuator
②. As the float/ displacer ③ rises following the liq-
uid level, it raises the attraction sleeve
④ into the field of
the magnet, which then snaps against the non-magnetic
enclosing tube
⑤, 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.
pivot
return spring
rising level
falling 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.
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
CCE
➀
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
FM/CSA
➁
Non-Hazardous area
Explosion proof area –
Groups B, C, D, E, F & G Type NEMA 4X/7/9
SAA
➁
Explosion proof area
LRS Lloyds Register of Shipment (marine applications)
GOST/ Russian Authorisation Standards
GOSGORTECHNADZOR
➁
Other approvals are available, consult factory for more details
➀ For CCE approved units, use the ATEX explosion proof model
numbers.
➁ Consult factory for proper model numbers.
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