Model 27

Level Transmitters
27 Liquid-Level Controller
Introduction
Features & Benefits
Flexible shaft design has no process-wetted pivots or links
to foul
Actuation motion of 1/32" provides precise measurement
Wide variety of flange sizes and materials simplify mounting
Standard process wetted parts are 316SS, improving
corrosion resistance
Description
The Model 27 Liquid-Level Controller consists of a float
mounted on a short float arm connected to the free-end of a
packless flexible shaft. The fixed-end of this flexible shaft is
attached to a standard flange.
The tubular shaft has a formed center section (similar to a
bourdon tube in cross section), which permits only vertical
float motion. The rigid float arm extension within the shaft
transmits the float motion to the air pilot for operation of a
diaphragm-type motor control valve.
The Model 27 Liquid-Level Controller operates on the change
in buoyant force of the float-not the motion of the float riding
on a changing liquid level. A buoyancy change of less than
six ounces will provide full actuation of the pilot valve or
contact switch. The Model 27 also has limit stops to maintain
the shafts within the elastic limit.
The float has a suitable margin of safety, allowing it to operate
in liquids having a minimum specific gravity of 0.50. A wide
range of specific gravities and level-change requirements can
be accommodated via elliptical, cylindrical, and other
special floats.
These units can be mounted on the direct side of a vessel
flange or externally mounted in a float chamber. Standard
piping connections on the float chamber are 1" NPT.
Specifications
Pressure
Full vacuum to flange rating
Temperature
Min. 32° F (0° C), Max. 350° F (177° C)
Specific Gravity
Electrical Classification
FM approved as: Explosion-Proof for Class I, Groups C & D,
Div. 1 service.
Dust Ignition-Proof for Class II, Groups E, F & G,
Div. 1 service. Suitable for Class III, Div.1 hazardous locations.
Float Size Table
Material
Ball Float Size
316 SST
Hastelloy C
3-1/2" Dia.
4" Dia.
5" Dia.
X
X
X
X
Suitable for
minimum
specific
gravity of:
0.5
0.35
0.25
Options
Special Temperature Ranges
Elastomers and enclosure construction optimized for the
following temperature ranges:
• 300-700°F (150 to 371°C)
• Below 32°F (0°C)
Elastomer Coatings
Coating of all wetted parts to increase corrosion resistance
Available coatings: Neoprene, TFE/PTFE, Kynar
0.50 Min.
Switch Rating
SPDT; 10A contacts; 125, 250, or 480 Vac
4.43
4
Level Transmitters
27 Liquid-Level Controller
Technical data
Model Number
Float Chamber1,2 Part Numbers
Liquid-Level Controller
Flange Size
Float
Chambers
4”
Steel
Casting
Type 316
SS Casting
6”
Welded
Steel
Pressure
Rating
Part No.
Part No.
Part No.
150#
300#
8537-1
8537-51
8537-201
8537-224
8537-46
8537-47
Mounting Dimensions
Flange or Connection Material
• Steel
• Stainless Steel
Flange Size and Rating
• 4" - 150#
• 4" - 300#
• 6" - 150#
• 6" - 300#
• 1-1/2" Threaded Connection
Operating Temperature (Electric Only)
• Low, under 32° F (0°C)
• High, over 350° F (177°C)
• Normal, between 32-350° F (0-177°C)
Options
• Float Chamber
• Reverse Acting (Pneumatic Only)
• Tee Assembly (for Top Mounting)
Order No.
27■■■■
▲▲▲▲
C
S
415
430
615
630
15
L
H
N
C
R
T
4
Standard
A
FlangeFlange Bolt
Class Size
Dia.
Circle
Steel
150
Steel
300
Steel
400
Steel
600
7-1/2
9-1/2
7-7/8
10-5/8
7-7/8
10-5/8
8-1/2
11-1/2
4
6
4
6
4
6
4
6
9
11
10
12-1/2
10
12-1/2
10-3/4
14
B
Bolt
C
D
E3
H
J
K
L
Flange Tee:
Face Chamber: Chamber: Chamber: Chamber:
No. Size Thick- Center
to
Center
Lenght
Body
Height
ness to Face
Ball
to Face
to Face Diameter at Conn.
8
5/8 1-5/16 6-1/2
4-3/4
6-1/2
11-3/8
5-3/4
8-1/2
8
3/4
1
8
4-11/16
6-1/2
12-5/8
6-5/8
9-1/2
8
3/4
1-1/4
7
4-7/16
6-1/2
11-3/8
5-3/4
8-1/2
12
3/4 1-7/16 8-1/2
4-1/4
6-1/2
12-5/8
6-5/8
9-1/2
8
7/8
1-3/8
8
4-3/4
Standard 4"-150# and 4"-300# cast-steel
12
7/8
1-5/8
9-3/4
4-3/4
chambers have 1-1/2" I.P.S. connections.
8
7/8
1-1/2
8-1/2
4-3/4
Other chambers can be furnished with 1-1/2"
or 2" I.P.S. connections. Data will be furnished on
12
1
1-7/8
11
4-3/4
request.
1) Chambers are constructed with 1-1/2" female NPT connections, top and bottom.
2) Chambers not listed above are considered special and will be priced on application.
3) F = E + diameter of ball.
4.44
Level Transmitters
27 Liquid-Level Controller
Technical data
4
Vertical Float
In order to provide for vertical motion
of the float, the mounting nozzle should
be installed with its flange face
vertical and the bolt holes straddling
the center line (shown to the left).
Controllers can be furnished for
installation in a tee on top of the tank.
If the vertical extension is greater than
24", or if the liquid level can be disturbed by surges, a suitable baffle or
cage that does not touch the float
should be installed.
Displacer Chamber
As shown to the right, a displacer chamber is recommended if
the liquid level can be disturbed by surges. Shut-off valves are
also advisable to allow the controller to be removed without
shut-down. Provisions can be made to periodically flush-out
the displacer chamber by connecting a purge line.
4.45