Deadweight Tester / Pressure Balance
Model LR-Cal LDW-P
Pneumatic, max. 100 bar (1500 psi)
Deadweight Tester / Pressure Balance (Primary Pressure Standard),
pneumatic, Ranges from -0,03...-1 bar to 0,4...100 bar and -0,435...-14 psi to 5,8...1500 psi.
Total uncertainty of measurement ±0.008% or ±0.015% of measured value.
Applications:
- Primary standard for defining the pressure scale in a range up to 100 bar pneumatic
- Reference instrument for calibration laboratories and factory for the testing, adjustment and calibration of pressure measuring instruments
- Self-contained, complete, stand-alone system, also suitable for on-site use
Special features:
- Total measurement uncertainty down to 0.008% of measured value
- Factory calibration includes traceability to national standars, as standard. Optional with DAkkS calibration
- High long-term stability with recommended recalibration cycle every 5 years
- Masses manufactured from stainless steel and aluminium, local gravity adjustment possible at no additional charge
- The optional quck-change system of piston-cylinder system enables fast and secure exchange of the piston-cylinder system in order to change the measuring range without tools.
Description
LR-Cal LDW-P Description
Proven primary pressure standard
Deadweight Tester / Pressure Balances are the most accurate instrument available on the market for the calibration of electronic or mechanical pressure measuring instruments. The direct measurement of the pressure (p = F / A), as well as the use of high-quality materials enable a very small measurement uncertainty, in conjunction with an excellent long-term stability of 5 years (recommended in accordance with German Calibration Service DAkkS).
The deadweight tester / pressure balance has therefore been used for years in factory and calibration laboratories in national institutes, research laboratories and in industry.
Stand-alone operation
Due to its integrated pressure generation and the pure mechanical measuring principle, the model LR-Cal LDW-P is ideal for on-site use for maintenance and service.
Basic principle
Pressure is defined as the quotient of force and area. The core component of the model LR-Cal LDW-P is therefore a very pecisely manufatured piston-cylinder-system, which is loaded with masses in order to generate the individual test points.
The masses applied are proportional to the target pressure and this is achieved through optimally graduated weights. As standard, these masses are manufactured to the standard gravity (9.80665 m/s²), though the can be manufactured to a specific location (gravity) and also DAkkS-calibrated.
Easy operation
Depending on the instrument version the pressure is set via an integrated pump or via an external pressure supply by the use of control valves. For fine adjustment a very precisely adjustable spindle pump with a precision spindle running only within the pump body is mounted.
As soon as the measuring system reaches equilibrium, there is a balance of forces between the pressure and the mass load applied. The excellent quality of the system ensures that this pressure remains stable over several minutes, so that the pressure value for comparative measurements can be read without any problems, or also so that more complex adjustments can be carried out on the item under test.
High-performance instrument range
The LR-Cal LDW-P instrument base is available in 2 variants, depending on the required pressure range:
- Low-pressure pneumatic base
Up to max. 10 bar / 150 psi.
With integrated pressure generation through priming pump and spindle pump.
- High-pressure and Vacuum pneumatic base
Up to max. 100 bar / 1,500 psi.
Connection for an external pressure supply or vacuum supply
NOTE: if used with vacuum piston-cylinder-unit, this second version MUST with connection for external pressure/vacuum supply MUST be choosed.
As standard, both instruments bases are fitted with a connection for the piston-cylinder system with M20 x 2 female thread.
Optionally, a quick-release mechanism is available. This enables the piston-cylinder system to be changed quickly and safely without any tools.
The connection of the test item is made without tools using a quick-connection. Via the freely-rotating knurled nut, the test item can be oriented as required. As standard, a threaded insert with a 1/2" BSP female thread is provided. Other threaded inserts are available to connect the most common pressure measuring instruments.
Piston-cylinder system
LR-Cal LDW-P Piston-cylinder-system
Both the piston and cylinder are manufactured from Tunbsten Carbide. Caompared to other materials, Tungsten Carbide has a very small pressure and thermal expansion coefficients, which results in a very good linearity of the effective cross-sectional area of the piston and high measurment accuracy.
Piston and cylinder are very well protected in a solid stainless steel housing, against contact, impacts or contamination from outside. In addition, overpressure protection is integrated, which prevents the piston from being forced out vertically and avoids damage to the piston-cylinder system in the event of weight removal under pressure.
The weight discs are stacked on a bell jar which is fitted to the piston skirt. Due to the construction of the bell jar, the centre of gravity for the stacked weights is very low, which minimises both the side thrust on the piston-cylinder system and the friction. For relatively low starting pressures, a lighter aluminium plate can be used instead of the ball jar.
The overall design of the piston-cylinder unit and the very precise manufacturing of both the piston and the cylinder ensure excellent operating characteristics with a long free-rotation time, low sink rates and a very high long-term stability. Therefore the recommended recalibration interval is 5 years.
The standard connection for the piston-cylinder system is an M20 x 2 male thread.
A quick-connect system, for easy measuring range changes without tools, is available as an option.
Specification
LR-Cal LDW-P Specification set of masses
The standard set of masses (content depending on measuring range) is supplied in one or two wooden caes. In the datasheet (see DOWNLOADs) you find a table of number and weight and nominal pressure for each pressure range. To increase the sensitivity ("resolution"), we recommend set of trim-masses, see Accessories.
Should you not operate the instrument under reference conditions (ambient temperature 20°C, air pressure 1,013 mbar, relative humidity 40%), the relevant corrections must be made.
The masses are manufactured, as standard, to the standard gravity (9.80665 m/s²) although they can be adjusted for any particular location.
LR-Cal LDW-P Technical Data
| Pressure range 1) | bar | -0.03...-1 | 0.03...2 | 0.2...10 | 0.4...50 | 0.4...100 | |
| Required weights | kg | 5 | 10 | 10 | 10 | 20 | |
| Smallest step 2) | bar | 0.01 | 0.01 | 0.05 | 0.25 | 0.25 | |
| Nominal cross-sectional area of the piston | cm² | 5 | 5 | 1 | 0.2 | 0.2 | |
| Pressure range 1) | psi | -0.435...-14 | 0.435...30 | 2.9...150 | 5.8...500 | 5.8...1000 | 5.8...1500 |
| Required weights | kg | 5 | 10 | 10 | 7 | 13 | 20 |
| Smallest step 2) | psi | 0.1 | 0.2 | 1 | 5 | 5 | 5 |
| Nominal cross-sectional area of the piston | cm² | 5 | 5 | 1 | 0.2 | 0.2 | 0.2 |
| Genauigkeit 3) | ±0.015% of measured value (optional: ±0.008% of measured value) | ||||||
| Version | |||||||
| for ranges up to 10 bar | integrated pressure source (priming pump and spindle pump) | ||||||
| for ranges from 20 bar, and Vacuum | Pressure port for external pressure or vacuum supply | ||||||
| Connections / Media | |||||||
| Conection piston-cylinder system | M20 x 2 male thread; Optional: quck-connector (required for Vacuum range) | ||||||
| Connection for test item | Quick connector 1/2" BSP female thread as standard, freely rotating, changeable (for other threaded inserts, see accessories) | ||||||
| Pressure transmission medium | clean dry non-corrosive gases (e.g. air or nitrogen) | ||||||
| Connection for external pressure/vacuum supply | 6 mm SWAGELOK (R) tube fitting; max. 110% of the assigned measuring range; Only for pneumatic high-pressure version) | ||||||
| Materials | |||||||
| Piston | Tungsten Carbide | ||||||
| Cylinder | Tungsten Carbide | ||||||
| Set of masses | Stainless steel 1.4305 and aluminium, non-magnetic | ||||||
| Piping in instrument base | Low-pressure version: flexible hose from polyurethane, 4 x 0.75 mm High-pressure version: stainless steel 1.4571, 3 x 1 mm |
||||||
| Operating conditions | |||||||
| Operating temperature | °C | 18...28 | |||||
| Weight | |||||||
| Instrument base | kg | 18.0 (19.0 incl. optional quick connector) | |||||
| Piston-cylinder system | kg | 1.5 (5.7 incl. bell jar and aluminium plat in optional storage case) | |||||
| BAR vacuum mass set | kg | 13.1 (incl. piston-cylinder system in storage case) | |||||
| BAR basic mass set | kg | 16.2 (incl. storage case) | |||||
| BAR mass set extension | kg | 14.0 (incl. storage case) | |||||
| PSI vacuum mass set | kg | 13.0 (incl. piston-cylinder system in storage case) | |||||
| PSI basic mass set | kg | 12.5 (incl. storage case) | |||||
| PSI mass set extension 1 | kg | 11.0 (incl. storage case) | |||||
| PSI mass set extension 2 | kg | 18.5 (incl. storage case) only for pressure range 1,500 psi | |||||
| Dimensions | |||||||
| Instrument base | mm | W 400 x D 375 x H 265 | |||||
| Storage case for basic mass set | mm | W 400 x D 310 x H 310 | |||||
| Storage case for mass set extension | mm | W 215 x D 310 x H 310 | |||||
| Optional storage case for piston-cylinder system | mm | W 300 x D 265 x H 205 | |||||
| Certificate | |||||||
| Calibration | Factory certificate of calibration, traceable. Optional: DAkkS certificate | ||||||
1) Theoretical starting value; corresponds to the pressure value generated by the piston (by its own weight). To optimise the operating characteristics more weights should be loaded.
2) The smallest pressure change value that can be achieved based on the standard weight set. To reduce this, a set of trim masses is also available, see Accessories.
3) The accuracy from 10% of the measuring range is based on the measured value. In the lower range, a fixed error based on 10% of the range applies.
4) Measuring uncertainty assuming reference conditions (ambient temperature 20°C, air pressure 1,013 mbar, relative humidity 40%). Corrections mus be made if required.
LR-Cal LDW-P Scope of Delivery + Options
Scope of delivery:
- Base with adjustable feet
- Priming pump (not for high-pressure and Vacuum version)
- Spindle pump for pressure generation and fine adjustment
- Piston connection with M30 x 2 male thread
- Quick connector for test items with 1/2" BSP female threaded insert, changeable
- Piston-cylinder system with bell jar
- Basic mass set in carrying case
- Mass set extension in carrying case (dependent on the measuring range)
- Set of masses manufactured to standard gravity (9.80665 m/s²)
- Manual in Englisch and German language
- Factory calibration certificate, traceable to national standards
Options:
- Piston connection with quick-release connector (necessary for vacuum range)
- System with increased accuracy to 0.008%
- Set of masses manufactured to local gravity
- Fine increment weights
- Storage case for piston-cylinder system
- DAkkS calibration certificate
Accessories
LR-Cal LDW-P Accessories
| Order-Code | Description | Image |
| LDW-FMS-F1 |
The weights included in the standard scope of delivery are ideally suited for everyday use. If you would like to generate intermediate values, however, we recommend using a set of trim-masses. Set of trim-masses, class F1 |
 |
| LDW-FMS-M1 | Set of trim-masses, class M1 (1 x 50 g, 2 x 20 g, 1 x 10 g, 1 x 5 g, 2 x 2 g, 1 x 1 g, 1 x 500 mg, 2 x 200 mg, 1 x 100 mg, 1 x 50 mg, 2 x 20 mg, 1 x 10 mg, 1 x 5 mg, 2 x 2 mg, 1 x 1 mg |
|
| CPB5000-ADS |
As a standard, the deadweight tester / pressure balance is equipped with a quick connector for connecting the test item. For this purpose, various threaded adapters, which can be easily exchanged, are available. Additionally the sets of adapters include spare O-rings as well as a spanner, 32 flats and 14 flats, for exchanging the adapters. Set of adapters: 1/4" BSP, 3/8" BSP, 1/2" NPT, M20 x 1.5 |
 |
| CPB5000-ADS-NPT | Set of NPT adapters: 1/8" NPT, 1/4" NPT, 3/8" NPT, 1/2" NPT | |
| CPB5000-WA90 | Angle connection 90°, for test specimens with back mounting connection |  |
| CPB5000-TV-1000 | Purifier (without diaphragm), max. 1,000 bar, designed for measuring instruments (test items) where the fill fluid should not come into contact with the deadweight tester / pressure balance. | |
| CPB5000-R-SET | Set of O-rings (5 pcs. 8 x 2 and 5 pcs. 4 x 2.2) for piston connector and test item connector |  |
| CPB5000-PN-RS | Cleaning set for LR-Cal LDW-P piston-cylinder system |
DOWNLOADs
LR-Cal LDW-P Datasheet / Operating manual
Excel Sheet
MS Excel sheet to calculate corrections (air density, piston temperature, local gravity) and masses/pressure calculations.
