48-1
Valtek Part No. ??????
GENERAL INFORMATION
This bulletin is designed to assist in installing, calibrating,
troubleshooting and performing maintenance as re-
quired for the XL90 Series high-performance positioner.
Product users and maintenance personnel should thor-
oughly read and strictly follow the instructions con-
tained in this bulletin prior to operating the positioner.
Any questions concerning this product should be di-
rected to a Flowserve representative.
To avoid possible injury to personnel or dam-
age to valve parts, WARNING and CAUTION
notes must be strictly followed. Modifying this
product, substituting non-factory parts or us-
ing maintenance procedures other than out-
lined could drastically affect performance and
be hazardous to personnel and equipment.
The XL90 high-performance positioner is a two-stage
device and is designed for use in control loops where
fast response is required. The XL90 positioner is de-
signed to be modular and use the P/P module for 3-15
psi input signal or the NT 3000 Series Transducer
Module for 4-20 mA input signal.
The XL90 high-performance positioner is designed as a
four-way device, but can easily be converted to a three-
way device by plugging one of the output ports.
NOTE: The XL90 high-performance positioner must
use the I/P NT 3000 Transducer. The I/P 2000 Trans-
ducer is not acceptable for use with the XL90 Series
Positioner.
The XL90 positioner can handle supply pressures up to
150 psi; thus, a supply regulator is usually not required.
However,
a five micron air filter is required for pneu-
matic positioners and a coalescing filter is required for
I/P positioners.
NOTE: The air supply should conform to ISA
Standard S7.3 (a dew point at least 18
°
F / -8
°
C
below ambient temperature, particle size below 5
microns, oil content not to exceed one part per
million).
The XL90 Series positioner features an adjustable gain
of 400-1100:1. The medium gain setting is standard for
smaller actuators, while the high gain setting is used on
larger actuators (refer to ‘Gain Adjustment Procedure’
section for further details.)
POSITIONER OPERATION
The positioner schematic (Figure 1) shows an XL90
Series positioner connected for double-acting service
on a rotary rack-and-pinion actuator. Tension on the
feedback spring provides feedback to the positioner,
which varies as the stem position changes. The spring-
loading force is applied through the feedback linkage
and cam to the positioner’s input capsule.
Instrument signal pressure is applied between the
diaphragms in the input capsule. Therefore, the input
capsule serves as a force-balance member, matching
the valve stem position (as measured by tension on the
feedback spring) to the instrument signal.
XL90 Series
High-Performance
Positioner
