Moore Industries IPT Installation Manual

April 2016

170-701-00 F

Current to Pressure

Transmitter

IPT

Current to Pressure

Transmitter

IPT

All product names are registered trademarks of their respective companies.

Table of Contents

Introduction 1

Description 1

Instrument Air and Filtration Information 3

Application Information 5

Calibration 7

Installation 11

Theory of Operation 12

Maintenance 14

Troubleshooting 16

Drawings 16

i

Page 1

IPT

Introduction

This manual contains calibration and installation
information for the Moore Industries' Current-to­Pressure Transmitter (IPT). Along with a description
of the IPT, this manual contains information
regarding instrument air, filtration, applications and
recommendations. Related tables and illustrations
are provided for reference purposes.

This manual contains notes and cautions that must be
observed to prevent equipment damage or minor
inconveniences during calibration or installation of the
IPT. The following definitions describe these cap­tions:

A

NOTE

shall contain technical or literary information
of a helpful nature. This information is intended to aid
the reader's understanding of the subject being
discussed and/or minimize inconveniences while
performing technical tasks.

A

CAUTION

serious nature that if ignored may cause equipment
damage.

shall contain technical information of a

Description

Individual IPTs consist of two parts: the transmitter
section and an interlocking pneumatic mounting
block, which snaps onto a rail. Units that are ordered
without a mounting block will clip onto an RIR or SIR
(rack or surface mounted header), which supplies air
to each unit using only one pneumatic supply pipe.
Both mounting blocks and supply headers contain
self-sealing valves. Therefore, the IPT can be
removed and replaced without disturbing the pneu­matic connections or causing accidental venting of
the supply or output air.

Operation can be montiored or calibration performed
by using the electrical input and optional pneumatic
output test jacks. A red LED display, which indicates
the presence of an electrical input signal, is also
provided.

Table 1 contains the IPT equipment specifications,
including inputs, outputs, power requirements, and
performance characteristics.

Model Number. The IPT model number describes

the equipment type, functional characteristics, operat­ing parameters, any options ordered, and housing. If
all other documentation is missing, this number is
used to identify equipment characteristics. The model
number for the IPT is located on a label on the side
of the unit.

The IPT is a compact 2-wire current-to-pressure
transmitter that converts a standard process current
signal to a pneumatic output. In its compact alumi­num housing, the IPT snaps onto standard mounting
rails or optionally onto a header (RIR or SIR). Be­cause of the extremely low dynamic mass of the
transducer element, the unit can be mounted in any
position and it is also very insensitive to shock and
vibration.

Serial Number. Moore Industries maintains a

complete history on every unit it sells and services.
This information is keyed to the serial number. When
service information is required on the IPT,
it is necessary to provide the factory with this number.
The serial number is located near the model number.

Page 2

IPT

Characteristic Specification

Performance Accuracy: Less than 0.5% of span including the combined effects of

Table 1. IPT Equipment Specifications

Input Current: 4-20mA or 10-50mA
Output Pressure: 0.2-1 BAR, 1-0.2 BAR, 3-15 psig, 3-27 psig,

15-3 psig, 20-100 kPa, or 100-20 kPa

Zero: Adjusts zero to ±3% of span
Span: For 20mA input, adjusts 3-15 psig output to 15 psig ±1%

linearity, hysteresis and repeatability -- defined as independent linearity
per SAMA standard PMC 20.1 - 1973. (For 3-27 psig or 10-50 mA,
error not to exceed 1% of span).

Step Response: 0.3 seconds into 100 ml (6 cu. in.) at 90% of span
Supply Pressure Effect: Maximum 0.3% / 1.4 psig (0.3% / 0.1 Bar)
Mounting Position Effect: Negligible, unit can be mounted in any position

but should be calibrated in final orientation
Shock and Vibration Effect: Less than 0.5% for acceleration up to 10 g's
and frequency up to 80 Hz

RFI Effect: Negligible
Air Capacity: 1.6 SCFM, minimum
Air Supply: Instrument air only, filtered and regulated, 20 psig nominal,

30 psig without damage. For 3-27 psig output, 35 psig nominal, 40 psig
without damage.
Air Consumption: Dead ended 0.1 SCFM (0.18 kg/hr)

Front Panel LED: Red light emitting diode indicates presence of electrical input signal

Zero and Span: Multiturn potentiometers
+T, -T: Electrical test jacks for calibration; accepts 2mm (0.080 in) dia. x 12.7mm

(0.50 in) long phone tip plugs (handles should be less than 8mm or 0.32 in.
in diameter

Operating Range:
Temperature Effect: Less than 0.055%/°F (0.1%/°C)

Weight 20 oz. (0.57 grams)

Note: See Installation Section for physical dimensions.

–40°C to +85°C (–40°F to +185°F).

Page 3

IPT

Instrument Air and Filtration Information

NOTE

For optimum performance, the selection and

use of a good quality air filtration system is

essential. Most users find that it is much less

expensive and troublesome to design a system

that includes good air filtration than deal with

downtime and repairs later.

To assure the maximum service life of an IPT, two
things are important: a clean, dry air supply and a
closed-loop application. Good air quality involves
removing solids, oil and water from the air after
compression. The cleaner the air, the longer the
time before servicing is needed.

Oversizing elements avoids performance abberations
and reduces maintenance time. Redundancy should
be used where possible to avoid shutdown during
maintenance.

Solids: Random solid dirt, such as pipe scale and

rust, is rarely a problem in compressed air instrument
systems. A good filter removes these solids. How­ever, if there is a desiccant dryer in the line, a high­efficiency sub-micron filter is recommended to
remove the highly abrasive sub-micron particles
produced by the dryer. A high-efficiency filter is
desirable in any system, and is often a feature of
coalescing-type filters.

Liquid Oil: Liquid oil is the most common problem in

compressed air instrument systems. A coalescing
filter removes sub-micron liquid droplets from the air,
and is usually supplied with an automatic drain.

A coalescing filter works by trapping oil and water
droplets in a bed of microfibers. The droplets run
together at fiber cross-over points, form large liquid
drops, and are forced by air flow to a drain. A filter
system consisting of a general purpose first-stage
filter (about 5 micron) and a high-efficiency coalesc­ing final filter is recommended to obtain contaminant­free air.

The exact location of the first-stage filter is not
important; it can be located just ahead of each final
filter, or a single first-stage filter can be located on a
main line to protect a number of final filters on branch
lines. Each final filter (coalescing) should be located
just ahead of each pressure regulator. In a new plant
installation, an oilless compressor may be used to
eliminate this problem.

Water: The amount of water in an air system de-

pends on temperature, pressure and the relative
humidity of the air. Therefore, this amount varies
widely with geographical location and weather.

Sufficient water must be removed to lower the dew
point of the air to a temperature below ambient. The
dew point (at line pressure) is expressed as the
temperature at which any moisture in the system
begins to condense.

Water may be removed using a number of tech­niques, including coalescing filters, refrigeration
dryers and desiccant dryers. In addition, a variety of
combinations and modular systems may be used for
special circumstances.

Care must be taken in the selection and location of
the filter, because cooling downstream of the filter can
cause more condensation of water. A coalescing
filter should be installed immediately upstream of the
pressure regulator. This type of filter removes most
of the water before the air enters the regulator. Air
leaving the regulator continues to dry due to the
expansion of the air.

For systems subjected to freezing temperatures, the
portion of the system that runs outdoors should have
a dryer installed. The dryer reduces the dew point
below the lowest expected outdoor temperature. A
desiccant dryer is used with a coalescing filter up­stream to keep the desiccant dryer from being
damaged by oil or being overloaded with excessive
condensed water. Another high-efficiency coalescing
filter is recommended downstream of the dryer, to
remove the desiccant fines.

Page 4

IPT

ISA Specifications: The Instrument Society of

America standard ISA-S73, 1975 (ANSI MC11.1-

1975) covers the air quality requirements for instru­ment grade air for use in pneumatic installations.

The dew point in outdoor installations must be at least

7.8°C (18°F) below the minimum local ambient
temperature. For indoor installations, the dew point
must be at least 7.8°C (18°F) below the minimum
interior temperature or 2°C (35°F), whichever is
greater. Although the ISA standard calls for a 35°F
dew point, this is often unnecessary indoors, and may
be unsatisfactory outdoors under freezing conditions.

Table 2. Recommended Filters for the IPT Air Supply

5 MICRON GENERAL PURPOSE PRE-FILTERS*

Max. No. MII Part No. Port Size Max. Flow
of IPTs Female NPT @ 100 PSIG

Filters that exceed the ISA specification provide very
inexpensive protection. Although the ISA specifica­tion calls for particle size not to exceed 3 microns
and oil content not to exceed 1ppm, most filter
manufacturers supply a line of coalescing filters that
remove particles down to sub-micron sizes (often

0.01 micron) while also removing oil to below ISA
1ppm specification (often to 0.01ppm).

2 800-802-42** 1/4 18
7 800-803-42 3/8 50
17 800-804-42 1/2 50
30 800-805-42 1/2 150

0.01 MICRON COALESCING FINAL FILTERS*

2 800-806-42** 1/4 4
7 800-807-42 3/8 15
17 800-808-42 1/2 35
30 800-809-42 1/2 60
62 800-810-42 1 125

* All filters are based on maximum (full) air flow from the IPT.
** These filters do not have sight glasses on the bowls.

Page 5

IPT

Application Information

The IPT
properly. In a closed loop, it is possible to measure
the controlled variable, to determine if a deviation
from the desired value exists, and to automatically
provide feedback for actuator loading pressure.

The IPT cannot operate in an open loop. An open
loop has inherent limitations that are not consistent
with precise control, such as: long term drift of the
loop dynamics, load fluctuations that require constant
adjustments of the actuator loading pressure, and
quality variations because of inconsistencies between
operating personnel. A controlled variable cannot be
directly measured in an open loop; this prevents
compensating adjustments to the system input. If an
IPT is installed in an open loop, it appears to drift due
to the lack of corrective feedback.

Recommendations

Any approach to providing good instrument air quality
should evaluate the worst case air flow and ambient
temperature of the location. This is required to
determine sizing of the air system elements. A
knowledge of yearly humidity cycles is also important
for this evaluation.

must be

installed in a closed loop to operate

The IPT requires periodic maintenance. The fre­quency of the service depends on the environment in
which the unit operates and the quality of the instru­ment air supplied. Service in the field is limited to
visual inspection and cleaning of the input nozzle filter
screen on the IPT and servicing of the compressed
instrument air filtration system. The unit may be
returned to the factory for complete
disassembly, cleaning, and servicing on a periodic
basis.

The use of coalescing filters with retention of 0.01
micron particles and droplets is recommended; they
remove all undesirable traces of oil and water drop­lets. Proper placement with respect to the
regulator(s) may eliminate the need for dryers, except
when coalescing filters are exposed to freezing
(keeping in mind that the dew point of the purified air
must be kept below worst case ambient).

Figures 1 and 2 illustrate typical non-redundant
systems with multiple branch lines. They both work in
any environment above freezing and differ only in the
placement of the general purpose first-stage filter.
Gages, valves, and differential pressure indicators
(for filter service monitoring) are not shown. It is
recommended that filters with integral service life
indicators or differential pressure indicators be used
to help ensure proper servicing, as well as redun­dancy to avoid shutdown during servicing.

CAUTION

Before placing IPTs in service, all pneu-

matic lines and mounting blocks or headers

(SIRs or RIRs) should be "blown down" to

purge contamination and condensation

deposited during piping and installation.

Also blow down lines to loads, since all

output air vents back through the IPT, and

there are never filters installed to trap these

contaminants (normally only present at
start-up). It is recommend this be done for
at least an hour, longer if there is evidence

of water or oil coming through.

Figures 1 and 2 differ in the method used to remove
water. The use of a desiccant type dryer (figure 2)
requires upstream filtration to prevent oil contamina­tion of the dessicant, as well as downstream filtration,
to prevent desiccant fines from introducing new
contamination.

The service life of an IPT is directly proportional to the
cleanliness and dryness of its air supply. The small
additional cost of providing high-qulaity air ensures a
longer, more trouble-free service life for the unit.