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アクセサリー Emerson Fisher 249のPDF 取扱説明書をオンラインで閲覧またはダウンロードできます。Emerson Fisher 249 16 ページ。 Cageless displacer sensors

249 Cageless Sensors

July 2015

A torque tube assembly (figure 2) and displacer provide an indication of liquid level, interface level, or density/specific

gravity. The torque tube assembly consists of a hollow torque tube with a shaft welded inside it at one end and

protruding from it at the other end.

Figure 2. Typical Side‐Mounted Cageless Displacer

TRAVEL STOP ASSEMBLY

DISPLACER ROD

DISPLACER

TORQUE TUBE

W0172‐1

The unconnected end of the tube is sealed by a gasket and clamped rigidly to the torque tube arm, permitting the

protruding end of the shaft to twist and therefore transmit rotary motion. This allows the interior of the torque tube to

remain at atmospheric pressure, thus eliminating packing and the disadvantages of packing friction.

The displacer always exerts a downward force on one end of the displacer rod. The other end of the displacer rod rests

on the knife‐edge of the driver bearing. A keyed shaft on the bearing end of the displacer fits into a socket on the

outside of the welded end of the of the torque tube assembly.

A change in liquid level, interface level, or density/specific gravity buoys up the displacer by a force equal to the weight

of the liquid displaced. Corresponding vertical movement of the displacer results in angular movement of the displacer

rod around the knife edge. Since the torque tube assembly is a torsional spring which supports the displacer and

determines the amount of movement of the displacer rod for a given displacement change, it will twist a specific

amount for each increment of buoyancy change. This rotation is brought through the torque tube arm by the

protruding rotary shaft. A controller or transmitter attached to the end of the rotary shaft converts the rotary motion

into varying pneumatic or electric signals.

Unless otherwise noted, all NACE references are to NACE MR0175-2002.

Type Number Description

D 249BP—CL150, 300, 600 steel top‐mounted sensor

D 249CP—CL150, 300, 600 stainless steel top‐mounted sensor

KNIFE EDGE BEARING

W1800‐1

Instruction Manual

D200100X012