LR-Cal LDW-HK deadweight tester / pressure balance
hydraulic, up to 1,200 bar
Accuracy up to ±0.025% of measured value

Hydraulic, compact design
Pressure ranges from 1...120 bar to 10...1,200 bar
and from 10...1,600 psi to 100...16,000 psi
Accuracy ±0.025% or ±0.05% of measured value

Scheme:
LR-Cal LDW-HK
with bell as mass carrier
(higher pressures)

LR-Cal LDW-HK
without bell

Scheme:
LR-Cal LDW-HK
without bell
(lower starting pressures)

Description

LR-Cal LDW-HK description

Proven primary standard
Pressure balances / deadweight tester are the most accurate devices 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 allow a very small measurement uncertainty in combination with an excellent long-term stability of 5 years (recommendation according to the German Calibration Service (DAkkS). Deadweight tester have been used for years in factory and calibration laboratories of industry, national institutes and research institutes.

Autarkic operation
Due to the integrated pressure generation as well as the purely mechanical measuring principle, the LR-Cal LDW-HK pressure balance is also ideally suited for on-site use, maintenance and service.

Basic principle
Pressure is defined as the quotient of force and area. Accordingly, the heart of the LR-Cal LDW-HK pressure balance is a very precisely manufactured piston/cylinder system that is loaded with mass supports to generate the individual test points.

The mass support is proportional to the target pressure and is achieved by optimally graduated disc weights. These disc weights are manufactured as standard to the standard acceleration of gravity of 9.80665 m/s², but can also be optionally adapted to their specific location of use and also DAkkS-calibrated.

Simple operation
The integrated dual-range spindle pump enables rapid filling of the test system and trouble-free pressure buildup up to 1200 bar (16000 psi). At the same time, the precisely adjustable spindle pump also serves for fine pressure adjustment. An operating diagram for pressure generation to facilitate quick and easy operation is located on the top of the device.

As soon as the measuring system is then in a floating state, there is a balance of forces between the pressure and the mass supports. Due to the excellent workmanship of the system, this pressure remains stable for several minutes, so that the pressure values for comparative measurement or even more extensive adjustment work on the test specimen can be carried out without any problems.

Compact device design
The LR-Cal LDW-HK deadweight tester is also characterized by its compact dimensions, which do not change even during operation due to the rotary spindle running only inside the pump body.
With its compact dimensions, the extremely robust ABS plastic housing and the associated low weight, the LR-Cal LDW-HK pressure balance is also particularly suitable for on-site applications.

Special features:

Total measurement uncertainty up to ±0.025% of measured value
With traceable factory calibration certificate as standard (option: DAkkS calibration certificate)
Very high long-term stability, recommended recalibration only every 5 years
Mass disks made of stainless steel, optional adaptation to local gravitational acceleration of the place of use possible
Compact dimensions

Applications:

Primary standard for the measurand pressure, up to max. 1,200 bar (16,000 psi), hydraulic
Reference instrument for factory and calibration laboratories for testing, adjusting and calibrating pressure measuring instruments of all types
Self-sufficient complete system, also suitable for on-site use.

Piston cylinder system

LR-Cal LDW-HK piston cylinder system

The pistons and cylinders of the LR-Cal LDW-HK deadweight tester are made of tungsten carbide. This material pairing has very low pressure and temperature expansion coefficients compared to other materials, which bring very good linearity of the effective piston cross-sectional area and high accuracy.

Piston and cylinder are very well protected against contact, shock or contamination from the outside in a solid stainless steel housing. At the same time, an overpressure safety device is integrated to prevent the piston from being pushed out vertically, thus preventing damage to the piston/cylinder system in the event that mass discs are removed under pressure.

The disc weights are stacked on a bell that is placed on the piston skirt. The design of the bell provides a very low center of gravity for the weights placed on top, minimizing lateral forces on the piston/cylinder system and friction. For smaller starting pressures, the disc weights can also be stacked directly on the piston skirt without using the bell.

The overall design of the piston/cylinder unit and the precise manufacture of the piston and cylinder ensure excellent running characteristics with a high free rotation time and low sink rates. This ensures very high long-term stability. The recommended recalibration cycle is therefore five years, depending on the conditions of use.

LR-Cal LDW-HK piston cylinder system
with mass discs
without bell, directly placed on piston
for lower starting pressures

Scheme: LR-Cal LDW-HK - masses placed without bell

LR-Cal LDW-HK without bell

LR-Cal LDW-HK piston cylinder system
with mass discs
with bell as a support for the disc weights
for higher starting pressures

Scheme: LR-Cal LDW-HK - masses placed with bell

LR-Cal LDW-HK with bell

Specification

LR-Cal LDW-HK specification

Pressure range "bar" 1)	[bar]	1...120	2.5...300	5...700	10...1,200
Required masses	[kg]	41	50	58	50
Smallest step 2) standard mass set	[bar]	1	2,5	5	10
Nominal cross-sectional area of the piston	[in²]	1/16	1/40	1/80	1/160
Pressure range "psi" 1)	[psi]	10...1,600	25...4,000	50...10,000	100...16,000
Erforderliche Massen	[kg]	38	47	58	47
Smallest step 2) standard mass set	[psi]	10	25	50	100
Nominal cross-sectional area of the piston	[in²]	1/16	1/40	1/80	1/160
Accuracy
Standard 3)	[% of measured value]	0,05
Option 3)	[% of measured value]	0,025
Pressure transmission medium	Hydraulic fluid based on VG22 mineral oil (0.5 l included in scope of delivery)
Material
Piston	Tungsten carbide
Cylinder	Tungsten carbide
Set of masses	Stainless steel, non-magnetic
Weight
Piston-cylinder system	[kg]	2.4
"bar"-mass set, incl. bell jar	[kg]	41.5	50.5	58.5	50.5
"psi"-mass set, incl. bell jar	[kg]	47.5	47.5	58.5	47.5
Optional carrying case for set of masses (2 pcs. required)	[kg]	5.8
Dimensions
Optional carrying case for set of masses (2 pcs. required)	[mm]	W 400 x D 310 x H 310

1) Theoretical starting value; corresponds to the pressure value generated by the piston or the piston and its make-up weights (bei their 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-HK base unit

Connection for piston-cylinder system:		3/4" BSP male
Test item connection:		1/2" BSP female thread, free-running, incl. adapter set to 1/4" BSP and 3/8" BSP female threads
Wetted parts:		Austenitic stainless steel, high tensile brass, nitrile rubber
Pressure transmission medium:		Hydraulic fluid based on VG22 mineral oil (0.5 l included in scope of delivery)
Reservoir volume:	[cm³]	170
Weight instrument base:	[kg]	13.5
Weight optional storage case for the base:	[kg]	8.5
Permissible operating temperature:	[°C]	18...28
Dimensions of the base:	[mm]	W 401 x D 397 x H 155

LR-Cal LDW-HK approvals + certificates

CE conformity: Pressure equipment directive 97/23/EG (module A)
Certificate of calibration: 3.1, traceable. Optional DAkkS certificate

Pressure ranges + mass tables

LR-Cal LDW-HK pressure ranges + mass tables

The following tables show the number of mass pieces within a mass set with their resulting nominal pressures for the respective measuring ranges.
If you do not use the device under reference conditions (ambient temperature 20°C, air pressure 1,013 mbar, relative humidity 40%), appropriate correction calculations must be applied.

The target weights are manufactured as standard to the standard acceleration of gravity of 9.80665 m/s², but can also be adapted to your local gravity.

Pressure unit "bar":

Measuring range [bar]	1...120 Nominal pressure per pc. [bar]	2,5...300 Nominal pressure per pc. [bar]	5...700 Nominal pressure per pc. [bar]	10...1,200 Nominal pressure per pc. [bar]
Piston and make-up weight	1 x 1	1 x 2.5	1 x 5	1 x 10
Piston, overhang (bell jar) and overhang make-up weight	1 x 20	1 x 50	1 x 100	1 x 200
Masses stackable on overhang (bell jar)	3 x 20	3 x 50	4 x 100	3 x 200
Masses stackable on piston	1 x 20 1 x 10 2 x 4 1 x 2 1 x 1	1 x 50 1 x 25 2 x 10 1 x 5 1 x 2.5	1 x 100 1 x 50 2 x 20 1 x 10 1 x 5	1 x 200 1 x 100 2 x 40 1 x 20 1 x 10

Pressure unit "psi":

Measuring range [psi]	10...1,600 Nominal pressure per pc. [psi]	25...4,000 Nominal pressure per pc. [psi]	50...10,000 Nominal pressure per pc. [psi]	100...16,000 Nominal pressure per pc. [psi]
Piston and make-up weight	1 x 10	1 x 25	1 x 50	1 x 100
Piston, overhang (bell jar) and overhang make-up weight	1 x 190	1 x 475	1 x 950	1 x 1,900
Masses stackable on overhang (bell jar)	5 x 200	5 x 500	7 x 1,000	5 x 2,000
Masses stackable on piston	1 x 200 1 x 100 2 x 40 1 x 20 1 x 10	1 x 500 1 x 250 2 x 100 1 x 50 1 x 25	1 x 1,000 1 x 500 2 x 200 1 x 100 1 x 50	1 x 2,000 1 x 1,000 2 x 400 1 x 200 1 x 100

Scope of standard supply

LR-Cal LDW-HK scope of standard supply

Base unit LR-Cal LDW-HK
Two-range pump for filling, pressure build-up and pressure fine adjustment
Piston connection with thread 3/4" BSP male
Test piece connection with 1/2" BSP female thread, free-running union nut
Adapter set for test piece connection 1/2" BSP male to 1/4" BSP female and 3/8" BSP female
Piston cylinder system, with bell
Bottle 0.5 liters with operating liquid (special oil VG22)
Mass set, manufactured to normal acceleration due to gravity 9.80665 m/s².
Tool and maintenance set
Factory calibration certificate (traceable)
Operating manual DE+EN