P.O. Box 40525 · Houston, Texas USA 77240-0525
Tel: 713·466·3552 · Fax: 713·896·7386
www.norriseal.com
1001-0113O — ©2013, January 2013
WA R N I N G !
Maximum allowable pressures for the
level controller body and the maximum
allowable pressure at the maximum tem-
perature for the level controller are shown
on the nameplate mounted in the case. If
pressure to the level controller is capa-
ble of exceeding these limits, install relief
valves or other over-pressure protection
devices in the pressure lines.
C A U T I O N !
When ordered, the controller body, dis-
placer material, and configuration were
selected to meet particular pressure, tem-
perature, and fluid conditions. Bodies and
displacers are limited in their operating
pressure and temperature ranges as well
as their ability to resist corrosion. Do not
apply any other conditions to the
controller without first contacting your
Norriseal sales office or your sales
representative.
P
RINCIPLE OF
O
PERATION
Force Balance Principle
The operation of the Series 1001,
1001A, and the 1001XL Level
Controllers is based on the Force
Balance Principle. A spring balances
the weight of a displacement type
sensing element. As liquid rises
around the displacer, the amount of
force available to the pilot is pro-
portional to the weight of the liquid
displaced. The force available is
transmitted to the pilot thrust pin
through a lever and fulcrum. The
higher the level, the greater the force
available to the pilot thrust pin.
The control is direct acting (rising
level increases pilot output) when
the pivot point of the lever is on the
spring side of the control case. The
control is reverse acting (rising level
decreases pilot output) when the
pivot point of the lever is on the
opposite side of the control case
from the spring.
Adjusting Proportional Band
Proportional band is the ratio of used
displacer length to total length of dis-
placer. For example, if 6 in. of level
change will develop a 3 to 15 psi out-
put signal with a 12-in.-long vertical
displacer, the level controller is said
to have a 50% proportional band.
By moving the fulcrum closer to the
pivot point, the proportional band is
increased. Likewise, by moving the
fulcrum toward the snap ring
decreases the proportional band. A
3 to 15 psi or 6 to 30 psi output sig-
nal may be obtained over any po tion
of the displacer by adjusting the
fulcrum.
Adjusting Level
The spring is used to balance the
weight of the displacer. As level
increases, the weight of the displacer
decreases. The spring tension
increases and is transmitted to the
O
PERATING AND
M
AINTENANCE
M
ANUAL
Series 1001, 1001A, 1001XL Level Control
Page 3 of 12
Figure 1 — Direct acting, right hand mount controller
Figure 2 — Adjusting proportional band
Pilot
Snap Ring
Sensitivity Fulcrum
Pivot Pin
Thumb Screw
Torque Bar
Balance Spring
Adjusting Knob
Level Adjusting Bar
Decrease
Proportional Band
Increase
Proportional Band
