Using Keller UK’s High-Precision Pressure Calibrators on Pressure Switches, Pressure Transmitters and Pressure Gauges

Table of Contents

Introduction
Calibrator Versions
     Full-Version
     Standard-Version
Specifications
     Options
     Logger
Description of the Low-Pressure Calibrator
     Connecting Test-Units
     Executing Functions and Commands
Medium Pressure Caibrator
High-pressure Calibrator
About Keller UK

Introduction

The pressure calibrators from Keller are high-precision calibration instruments that can calibrate pressure switches, pressure transmitters and pressure gauges. The low, medium ranges are pneumatic while the high ranges are hydraulic. A high-precision reference sensor, pressure generating pump and electronics are included in the portable housing.

The transmitter under test is connected to the pressure port of the calibrator and the signal is directly read out on the display. Several internal functions and performance features help the user in a number of different measuring tasks. Furthermore, the serial interface enables the transfer of the measured data onto a PC for further processing. The calibrator, including accessories, is supplied with a robust carrying case and is suitable for outdoor and on-site use.

Calibrator Versions

Two basic versions of the calibrator are offered

Full-Version

The Full-Version of the calibrator is a complete, self-contained transmitter testing unit. With internal supplies for the transmitter and the calibrator itself, the self-contained instrument is always ready for use. For a broad range of measuring and testing tasks, a broad selection of software functions are incorporated:

  • Mano displays the pressure and the maximum and minimum pressures
  • Mano* displays the pressure, the transmitter signal and the temperature
  • Hold freezes the actual measured values on the display
  • Tara sets the pressure display to zero (volatile)
  • Unit scales the display into different pressure units (bar, PSI, kPa…)
  • Leak determines the pressure decrease (or increase) over a pre-set time period
  • Rec records the measured values (the number of values and the interval are programmable)
  • Reso reduces or increases the resolution
  • Zero sets the pressure display to zero (permanently)
  • Pst records the switching points of pressure switches
  • Lin calculates the linearity error of the test transmitter * with transmitter connected

Standard-Version

The Standard-Version is restricted to the essential features for precision pressure generation only. For this simplified operation, this version does not incorporate the integral transmitter supply, nor the display of the transmitter signal, thus it does not incorporate the Pst and the Lin functions. Figure 1 illustrates an outline of the high pressure calibrator.

Figure 1. High Pressure Calibrator Outline Drawing.

Specifications

The specification of the pressure calibrators are:

Pressure Ranges (FS) bar -1…2 -1…10 -1…25 0…200 0…350 0…700
Overpressure bar 2,4 12 30 240 420 840
Total Accuracy (1) 0,1 %FS max.
Measuring Interval 0,5 sec. (1 second with transmitter or pressure switch connected)
 

(1) Includes linearity, repeatability, hysteresis, temperature and resolution of the display over the range 0..50 °C.

Electrical Characteristics

Electronic Supply Lithium-battery 3,6 V (included)
Battery Life > 200 days at continuous operation
Transmitter Supply (Full-Version only) max. 18 VDC (2 x 9 V batteries) or with 230 VAC adapter (included)

Environmental Characteristics

Operating Temperature 0…50 °C
Compensated Range 0…50 °C
Storage Temperature -20…60 °C
Display 0…50 °C
Air Humidity 5…95 % relative humidity

Mechanical Characteristics

Calibrator-Housing Polyamid 12
Weight 1,6 to 4,0 kg, depending on model
Pressure Connection Serto + different adapters
Protection IP 54
Hydraulic Oil (2) Type HLP 22 BP

(2) High range only.

Options

The optional accessories are:

  • Logger-Software for data transfer to PC and cable K101
  • Extended memory up to 8000 storage places for the Rec-function.

Logger

The Logger-Software enables the read-out of the stored data from the calibrator. The data transfer takes place through the serial interface on the PC. The calibrator is connected through a cable K101, which is supplied with the Logger software.

The Logger-Software provides many further processing possibilities of the read-out data, and meets all the requirements of modern Windows software:

  • Graphical Display
  • Tabulated Display
  • Export into other Windows Programs
  • Storage into Files.

Description of the Low-Pressure Calibrator

The calibrator combines a number of functions and performance features. The instrument is battery powered, hence highly suitable for outdoor use. The calibrator itself is powered by a 3.6 V battery. Test-units can either be powered by the internal 9 V batteries or external power supply. The low pressure calibrator generates pressure with both the hand-pump up to 10 bar and the vacuum-pump down to -850 mbar as well as the integrated fine pressure adjuster. The instrument’s advanced technology ensures that it can accurately measure both the generated pressure and output signal of a connected test unit. The calibrator has an internal memory for recording data. It can either be filled with the linearity measurements, the switching points of a pressure switch or with continuously measured recordings. This data can be transferred afterwards to a PC for evaluation via RS 232 serial interface. The calibrator is operated with the function key (F-key), marked by a pointed triangle. An additional key, the Hold-key, will freeze the display at any time during operation.

Connecting Test-Units

Adapter:

Included in the delivery of the calibrator are different test-unit adapters, one for each of the following transmitter types:

  • 4…20 mA / 0…20 mA transmitter
  • 0…10 V / 0…20 V transmitter
  • Pressure switch.

Executing Functions and Commands

The various functions one needs to be familiar with include:

Turn-Off

Press the function key until the command Off appears on the display. Release the key immediately and the instrument turns off.

Function-Key (F-Key)

The function key on the front of the instrument, marked by a pointed triangle, serves to operate the instrument.

Hold-Key (H-Key)

The Hold-Key, integrated in the back of the instrument housing, freezes the values during the Mano-Mode. It has additional functions in other modes.

Command Structure

When keeping the F-Key pressed, the functions Exe, Off, Mano, Tara, Unit, Leak, Pst*, Rec, Lin*, Zero, Reso and ascending numbers appear successively on the display.

Releasing the F-Key at a displayed function activates and leads into the function. This cycle (constantly pressing the F-Key and letting it go at a desired function) is called activation.

Within specific functions, the F-Key can execute additional commands (Exe, Step, Reset). Activating Off turns off the instrument. When starting the instrument again, the display will automatically lead into the function from which the instrument was previously turned off.

Activate Mano if normal operation is desired.

Exe: In Mano-Mode: To reset peak- and trough-pressure.

Off: To turn off the instrument.

Mano: To display the actual pressure generated, the units, peak- and trough pressure.

Tara: To set a new, volatile reference for the zero point (Tare).

Unit: To display the pressure in different units (Bar, Psi, kPA, mWC…).

Leak: To measure the pressure changes over a programmable time.

Pst*: To test pressure switches.

Rec: To record the measured values in programmable intervals.

Lin*: To determine the linearity of a test-unit.

Reso: To reduce the resolution by factor 10 or to return to the original resolution.

Zero: To write a new zero point into the non-volatile memory.

28, 29… Ascending numbers (have no function).

Medium Pressure Caibrator

The specifications of the Medium-Pressure Calibrator are:

Total Accuracy of displayed Pressure(1) ±0.1% FS (Full Scale), from 0…50 °C
Total Accuracy of displayed Test Unit Signal ±0.1% FS ±1 Digit
Resolution of Display  
    10 bar Calibrator 1 mbar
    20 bar Calibrator 1 mbar
    25 bar Calibrator 1 mbar
Overpressure FS + 10%
Selectable Pressure Units BAR / PSI / kPA / mWC (others on request)
Measurement Cycle 2 Measurements per Second
Displayed Temperature Temperature of Reference Sensor in °C
Storage Temperature -20…60 °C
Operating Temperature 0…50 °C
Compensated Temperature Range 0…50 °C
Air Humidity 5…95% Relative Humidity
Memory 900 Storage Places (8000 optional)
Power Supply of Calibrator-Electronics Lithium-Battery 3.6 V (not rechargeable)
Lithium-Battery-Life > 200 Days at continuous operation
Power Supply of Transmitter 2 x 9 V Batteries (not rechargeable)
Total Weight, including Batteries  ~ 2 kg
Dimensions (L x W x H) 350 (500) x 153 x 205 mm
Protection (only Standard) IP 65

(1) Includes linearity, repeatability, hysteresis, temperature error and resolution of the display

High-pressure Calibrator

The specifications of the High-Pressure calibrator are:

Total Accuracy of displayed Pressure(1) ±0.1% FS (Full Scale), from 0…50 °C
Total Accuracy of displayed Test Unit Signal ±0.1% FS ±1 Digit
Resolution of Display  
    200 bar Calibrator 10 mbar
    350 bar Calibrator 100 mbar
    700 bar Calibrator 100 mbar
Overpressure FS + 10%
Selectable Pressure Units BAR / PSI / kPA / mWC (others on request)
Measurement Cycle 2 Measurements per Second
Displayed Temperature Temperature of Reference Sensor in °C
Storage Temperature -20…60 °C
Operating Temperature 0…50 °C
Compensated Temperature Range 0…50 °C
Air Humidity 5…95% Relative Humidity
Memory 900 Storage Places (8000 optional)
Power Supply of Calibrator-Electronics Lithium-Battery 3.6 V (not rechargeable)
Lithium-Battery-Life > 200 Days at continuous operation
Power Supply of Transmitter 2 x 9 V Batteries (not rechargeable)
Total Weight, including Batteries ~ 2 kg
Dimensions (L x W x H) 350 (500) x 153 x 205 mm
Total Oil Chamber Volume 57 ml
Oil Type Type HLP 22 BP
Dead Volume 7,7 ml
Total Weight, including Batteries  ~ 3,9 kg
Dimensions (L x W x H) 315 (337) x 153 x 205 mm
Protection (only Standard) IP 65

(1) Includes linearity, repeatability, hysteresis, temperature error and resolution of the display

About Keller UK

KELLER is Europe's largest manufacturer of isolated piezoresistive pressure sensors and pressure transmitters. KELLER are a world leader in pressure sensing technology continually developing new materials and manufacturing processes, that is why this company remain successful.

This Company introduces a comprehensive range of products, from simple Pressure Capsules, to fully compensated digital pressure transmitters, also low- cost industrial pressure transmitters, digital pressure gauges, recording digital manometers. Modern advanced production techniques enable KELLER to offer competitive pricing for medium and high volume production orders. Customer engineered special products are easily accommodated.

KELLER supply Pressure Sensors to all industries and applications and are specialist in the following areas: Refrigeration, Oil & Gas 'down-hole', Water Depth, Hydraulics, Autoclave Sterilisers, Oceanology.

This information has been sourced, reviewed and adapted from materials provided by Keller UK.

For more information on this source, please visit Keller UK.

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