4
Tuffy Liquid Level Control with Pneumatic Switch
1.3
Mounting
The pneumatic Tuffy
®
Liquid Level Switch is available with a
2" NPT mounting bushing, a variety of flange mountings
and external cages for mounting outside of the vessel.
1.3.1 Mounting an NPT Tuffy
®
1. Apply either Teflon
®
tape or Petrolatum to the mounting
threads to prevent galling.
2. Engage the 2" NPT by hand to avoid damaging threads.
3. Using a pipe wrench, rotate the unit clockwise until threads
are tight in mounting. Ensure that the serial number plate is
on top. See Figure 1.
Caution:
The pneumatic Tuffy must be installed with the serial
number plate on top to ensure correct switching action.
1.3.2 Mounting a Tuffy with Flange
1. Have proper flange bolting and gasket on hand.
2. Carefully align mounting flange with the vessel mounting
flange.
3. Ensure that the flange gasket is seated properly. Install
flange bolts and nuts.
4. Tighten alternating flange bolts in a star pattern.
5. Install Tuffy into 2" NPT of mounting flange as described
in Section 1.3.1 above.
Caution:
Operation of all buoyancy type level devices should be done
in such a way as to minimize the action of dynamic forces on
the float or displacer sensing element. Good practice for
reducing the likelihood of damage to the control is to equal-
ize pressure across the device very slowly.
1.3.3 Mounting External Cage Tuffy
A typical Tuffy
®
external cage installation is shown in Figure 2.
1. Install cage so that tappings are within 3° of vertical in all
directions. Check installation with a level.
2. Mount cage as close to vessel as possible, to provide more
accurate level in cage. Long pipe runs may result in cooler,
denser liquid than that in the vessel and cause inaccurate
level in the Tuffy cage.
3. Use pipe of sufficient size and strength to support the
control. If necessary, provide a hanger or stand to help
support the weight of the cage.
4. All piping should be straight and free of low spots or pockets.
Lower liquid line should drain toward vessel and upper line
toward Tuffy cage.
5. Shut-off valves are recommended for installation between
the vessel and the cage assembly.
6. Once external cage is mounted, install pneumatic Tuffy into
cage per Section 1.3.1 or 1.3.2.
CL
Pressure
vessel
Shut–off
valve
Safety
check
valve
Shut–off
valve
Drain valve
Switch
actuation
level
1/4" NPT
inlet (A)
1/4" NPT
outlet (C)
1/4" NPT
inlet (B)
Figure 2
