Dead Weight Testers
Dead weight testers for pressurised air or neutral gas
Pressure ranges 0.1... 6 bar, 0.1 ... 10 bar and 0.1 ... 25 barDead weight testers are used for examination and calibration of pressure gauges and other pressure measuring instruments without using an external instrument. The main components are the measuring system, the valve units, the built-in screw pump for accurate pressure adjustment and the set of weights.
The measuring system itself consists of a precise lapped-in pair of piston and cylinder. During the measuring process the piston is forced up by the pressure produced with the built-in screw pump re-spectively with external pressure supply, while the regular weights and maybe further extra weights, if required for the designated test pressure, press it down.
With the built-in screw pump the test pressure can be adjusted to an equilibrium of the forces. When the forces on both sides of the piston are in balance, the piston will be floating, and the designated test pressure is reached exactly.
For simplifying the handling, the instrument-specific weights are already referred to each relevant determined piston area and stamped with the pressure unit (bar/kPa).
The influence of the friction between piston and cylinder is mini-mised by keeping piston and weights rotating while floating.The models described in this data sheet are available for pressure ranges 0.1 to 6, 0.1 to 10 resp. 0.1 to 25 bar.
PD 25Models
PD 6PD 10 Technical data
• Pressure range: PD 6 PD 10 PD 25 • Set of weights in bar / kPa
0.1 to 6 bar
0.1 to 10 bar 0.1 to 25 bar
Scope of delivery
• External pressurised air supply for PD 10 and PD 25 required, indeed as high as the pressures that have to be examined1) ; external pressurised air supply for PD 6 recommended (compare page 2) •
Accuracy of the adjusted examination pressure: better 0.05 % resp. 0.03 % (with official verification or DKD-approval) referred to the effective pressure. Up to 0.6 bar the maximum error is constantly ±0.3 mbar (at 0.05%) resp. ± 0.18 mbar (at 0.03%)
Beside the dead weight tester and the set of weights the scope of delivery comprises the following:• 1 operating instruction
• 1 canister with 1 litre special oil (drilling oil and sealing liquid)• 1 cover plate
• 1 special sealing for test item with 2 chambered o-rings• 4 o-rings as replacement
• 2 expansion plugs for N 6x1 (admission pressure connection) for models PD 6 and PD 10
• 2 plugs for "oil drains" (21, 26 compare page 3), already plugged in when being delivered
• Reference conditions for the granted accuracy:
ambient temperature + 20 °C ± 2 °C
accelaration of fall = 9.8102 m/s2
• Dimension of the crosssection of the measuring unit:
1.0 cm2 ± 0.2 % • Rotation of the weights: by electrical drive (220 VAC / 50 Hz / 45 mA)
• Connection for pressure gauges:
1 clamping sleeve G ½ and M 20x1.5 each • Connection for external pressurised air: plug connection
(Prestolock) for PA hose N 4 x 1, for PD 6 and PD 10 with expansion plug for N 6 x 1 • Medium: pressurised air or neutral gas, e.g. nitrogen
• Case: grey-painted Al-case (self-supporting cap), 3 machine mounts for the exact horizontal positioning
according to installed circular level • Case dimensions including star handle: (L x W x H) 490 x 480 x 330 mm (19.29" x 18.9" x 12.99")
Weights: (approx.) Dead weight tester Set of weights
Transport box dead weight tester Transport box set of weights
PD 6 28 kg 7 kg 21 kg 2 kg
PD 10 28 kg 16 kg 21 kg 5 kg
• Set of weights in kp/cm2; other set of weights upon request• Test certificate 3.1.B according to EN 10204 for indication accuracy
• Official verification or DKD-approval
(the installation location has to be specified for this)• Hose N 4 x 1 for Prestolock
• Fitting of the hose 4 x 1 on ¼" NPT male
Special versions and accessory
Operating instructions
(see also page 3, drawing 1...5b)
ATTENTION !
Please handle the dead weight tester only at the hanholds for transporting and repositioning, but never at the measuring system. Otherwise this could lead to serious damage.Putting into operation
The dead weight tester and the set of weights are supplied in separate wooden transport boxes (PD 25 two boxes for set of weights).
Please release the transport screws before taking the instrument out of the transport boxes.
Place the instrument at the workplace and adjust it via the in-tegrated circular level by screwing in the machine mounts. The machine mounts have orifices for mounting to the workplace.Screw in the clamp handles and the helicoidal gear pump head.Plug in the motor. ...
• Required working surface: 520 x 450 mm (20.47" x 17.72")•
1)
PD 25 28 kg 31 kg 21 kg 5+2 kg
T o reach these pressures, a gas cylinder (nitrogen) or an air pressure intensifier can be applied.
10912
12/11
Connection of the admission pressure
The admission pressure connection happens optionally via a P A-hose N 4 x 1 or with an expansion plug for N 6 x 1 to plug con-nection (9) (Prestolock), for PD 25 only via hose N 4 x 1.
T o protect the dead weight tester against impurities, an air control unit consisting of pressure regulator and filter (pores 10-20 µm with oil and water separator) has to be applied to the air control unit.The pressure regulator has to be limited to the maximum final value.
Refilling of the oil reservoir (3)
Examination of pressure gauges without external admission pressure – only model PD 6 –
If for PD 6 no admission pressure is available, the designated pres-sure can be produced with the helicoidal gear pump and change-over valve (7) as follows:
Close dosing valve "Vordruck" (8) (admission pressure).
Switch over the change-over valve "Spindelpumpe" (7) (helicoidal gear pump) to "Pumpe aus" (pump off).
Move the piston of the helicoidal gear pump (2) by left-turning of the star handle all the way to the stop.
Switch over the change-over valve (7) to "Pumpe ein" (pump on).Move the piston of the helicoidal gear pump by right-hand turning all the way up to the stop.
Switch over the change-over valve (7) to "Pumpe aus" (pump off). T urn the piston of the pump back all the way to the stop.Switch over to "Pumpe ein" (7) (pump on).
Please repeat this process as long as the designated pressure (max. 6 bar) is reached.Set of weights
ATTENTION ! Treat the set of weights carefully and avoid all kinds of damage! The set of weights are delivered in one wooden
box for models PD 6 and PD 10 and in two wooden boxes for model PD 25.
The instrument is being supplied in a filled condition.
Oil must be refilled immediately when the oil level is no longer visible
through the window of the oil clumn.
For refilling the change over valve (18) has to be switched to "Ent-lüften" ("vent"). Remove the screw (24) from the oil tank, fill in the oil up to the upper rim and close the reservoir by screwing in the screw (24).
Use only the oil included in shipment respectively reordered oil, which will be delivered upon request.
Advice
After approximately 40 operating hours the overflow oil of the system (via outlet 21) and the overflow oil of the measuring cylinder (via outlet 26) should be emptied in depressurised condition.
Examination of pressure gauges at connected admission pressure
All valves are closed.
operating without external pressure, compare below.)
The test item has to be screwed in densely into the clamping sleeve at the test connection (13).
Afterwards please open the pressure gauge valve "Prüfanschluss" (11) (test connection).
Place the spindle and pump approximately in the middle between front and back arrester, so that the pressure can be both, increased and decreased via the star handle of the spindle.
Put the weights according to the designated pressure on the base plate (14).
Switch the change-over valve (18) to "Vordruck" (admission pres-sure).
Open the dosing valve "Vordruck" (8) (admission pressure) slowly and reclose it.
Switch on the electric drive via the switch (22).
The pressure has to be adjusted via the star handle of the spindle so that the piston is placed in the measuring position (drawing 5a or 5b).
ATTENTION!
During measuring operation the piston neither may touch the lower nor the upper arrester.
Except of the 5 bar weight the weights can be laid down during ongoing operation.
The motor and the measuring system have to be stopped respectively switched off before laying down the 5 bar weights.
Please do also stop the motor before pressure relief.
The weights and the base plate [14 (basic load)] are marked with bar and kPa for the pressure, which is produced on the dead weight tester, as well as the instrument identification number and the final value.The base plate [14 (basic load)] without weights produces a pressure of 0.1 bar.
We recommend to work with additional weights to simplify the app-lying of further weights.
An additional weight is a weight as addition to the basic load 0.1 bar, to produce a pressure of 1 bar, respectively 5 bar.
First you apply an additional weight (0.9 or 4.9 bar) and then the next weights, according to the designated pressure.
In the lower range additional weight 0.9 bar is used and for above 5 bar (for PD 10 and PD 25) the additional weight 4.9 bar is used.The set of weights is composed as follows.PD 6
5 weights 1 weight 1 weight 4 weights 1 weight 4 weights PD 101 weight 1 weight 4 weights 1 weight 1 weight 4 weight 1 weight 4 weights PD 254 weights 1 weight 4 weights 1 weight 1 weight 4 weights 1 weight 4 weights
1 0.9 0.5 0.1 0.05 0.01 5 4.9 1 0.9 0.5 0.1 0.05 0.01 5 4.9 1 0.9 0.5 0.1 0.05 0.01
bar
bar (additional weight)bar bar bar bar
bar
bar (additional weight)bar
bar (additional weight)bar bar bar bar
bar
bar (additional weight)bar
bar (additional weight)bar bar bar bar
For pressure relief down to "0 bar" the admission pressure also has to be relieved by switching over the change-over valve (18) to "Entlüften" (ventilation) and opening the dosing valve "Vordruck" (admission pressure).
At operation of the change-over valves (7 + 18) please pay attention to a clear locking of the lever position above the nameplates.
1
The smallest graduation of the supplied set of weights is 0.01 bar.Correction weights for smaller graduations and for corrections of ambient parameter deviations of the standard conditions are avai-lable upon request.
Drawing 1Drawing 2
1 = Measuring system
2 = Helicoidal gear pump with star handle 3 = Oil reservoir 4 = Electrical motor
5 = Reading device (stationary pointer) 6 = Case Drawing 3 7 = for PD 6: change-over valve helicoidal gear pump ("Pumpe ein", "Pumpe aus", "Entlüften") (pump on, pump off, vent)
8 = Dosing valve "Vordruck" (admission pressure) 9 = "Eingang Vordruck" (inlet admission pressure)10 = "Entlüftung Vordruck" (ventilation admission pressure)
11 = Pressure gauge valve "Prüfanschluss" (test connection)
(only for PD 6! compare page 2)
12 = T est connection
13 = Clamping sleeve (SW 27)14 = Base plate (basic load)15 = Union nut
Drawing 5 a16 = Measuring piston
17 = Measuring cylinderReference edge of
(see drawing 3 for details of the Drawing 418 = Change-over valve for external the reading device for measuring system)
small weights admission pressure
("Vordruck", "Zu", "Entlüften") (admission pressure, closed, vent)19 = Machine mounts20 = Circular level
21 = "Ölablass" (oil drain port)Drawing 5 b (overflow of the system)
22 = Switch of the electrical motor
Reference edge of
23 = Calibration plate (for official verification)the reading device for 24 = Screw oil reservoirsmall weights25 = Nameplate
26 = "Ölablass Messzylinder"
(oil drain port measuring cylinder)
1
Dead Weight Testers
Dead weight testers for pressurised air or neutral gas
Pressure ranges 0.1... 6 bar, 0.1 ... 10 bar and 0.1 ... 25 barDead weight testers are used for examination and calibration of pressure gauges and other pressure measuring instruments without using an external instrument. The main components are the measuring system, the valve units, the built-in screw pump for accurate pressure adjustment and the set of weights.
The measuring system itself consists of a precise lapped-in pair of piston and cylinder. During the measuring process the piston is forced up by the pressure produced with the built-in screw pump re-spectively with external pressure supply, while the regular weights and maybe further extra weights, if required for the designated test pressure, press it down.
With the built-in screw pump the test pressure can be adjusted to an equilibrium of the forces. When the forces on both sides of the piston are in balance, the piston will be floating, and the designated test pressure is reached exactly.
For simplifying the handling, the instrument-specific weights are already referred to each relevant determined piston area and stamped with the pressure unit (bar/kPa).
The influence of the friction between piston and cylinder is mini-mised by keeping piston and weights rotating while floating.The models described in this data sheet are available for pressure ranges 0.1 to 6, 0.1 to 10 resp. 0.1 to 25 bar.
PD 25Models
PD 6PD 10 Technical data
• Pressure range: PD 6 PD 10 PD 25 • Set of weights in bar / kPa
0.1 to 6 bar
0.1 to 10 bar 0.1 to 25 bar
Scope of delivery
• External pressurised air supply for PD 10 and PD 25 required, indeed as high as the pressures that have to be examined1) ; external pressurised air supply for PD 6 recommended (compare page 2) •
Accuracy of the adjusted examination pressure: better 0.05 % resp. 0.03 % (with official verification or DKD-approval) referred to the effective pressure. Up to 0.6 bar the maximum error is constantly ±0.3 mbar (at 0.05%) resp. ± 0.18 mbar (at 0.03%)
Beside the dead weight tester and the set of weights the scope of delivery comprises the following:• 1 operating instruction
• 1 canister with 1 litre special oil (drilling oil and sealing liquid)• 1 cover plate
• 1 special sealing for test item with 2 chambered o-rings• 4 o-rings as replacement
• 2 expansion plugs for N 6x1 (admission pressure connection) for models PD 6 and PD 10
• 2 plugs for "oil drains" (21, 26 compare page 3), already plugged in when being delivered
• Reference conditions for the granted accuracy:
ambient temperature + 20 °C ± 2 °C
accelaration of fall = 9.8102 m/s2
• Dimension of the crosssection of the measuring unit:
1.0 cm2 ± 0.2 % • Rotation of the weights: by electrical drive (220 VAC / 50 Hz / 45 mA)
• Connection for pressure gauges:
1 clamping sleeve G ½ and M 20x1.5 each • Connection for external pressurised air: plug connection
(Prestolock) for PA hose N 4 x 1, for PD 6 and PD 10 with expansion plug for N 6 x 1 • Medium: pressurised air or neutral gas, e.g. nitrogen
• Case: grey-painted Al-case (self-supporting cap), 3 machine mounts for the exact horizontal positioning
according to installed circular level • Case dimensions including star handle: (L x W x H) 490 x 480 x 330 mm (19.29" x 18.9" x 12.99")
Weights: (approx.) Dead weight tester Set of weights
Transport box dead weight tester Transport box set of weights
PD 6 28 kg 7 kg 21 kg 2 kg
PD 10 28 kg 16 kg 21 kg 5 kg
• Set of weights in kp/cm2; other set of weights upon request• Test certificate 3.1.B according to EN 10204 for indication accuracy
• Official verification or DKD-approval
(the installation location has to be specified for this)• Hose N 4 x 1 for Prestolock
• Fitting of the hose 4 x 1 on ¼" NPT male
Special versions and accessory
Operating instructions
(see also page 3, drawing 1...5b)
ATTENTION !
Please handle the dead weight tester only at the hanholds for transporting and repositioning, but never at the measuring system. Otherwise this could lead to serious damage.Putting into operation
The dead weight tester and the set of weights are supplied in separate wooden transport boxes (PD 25 two boxes for set of weights).
Please release the transport screws before taking the instrument out of the transport boxes.
Place the instrument at the workplace and adjust it via the in-tegrated circular level by screwing in the machine mounts. The machine mounts have orifices for mounting to the workplace.Screw in the clamp handles and the helicoidal gear pump head.Plug in the motor. ...
• Required working surface: 520 x 450 mm (20.47" x 17.72")•
1)
PD 25 28 kg 31 kg 21 kg 5+2 kg
T o reach these pressures, a gas cylinder (nitrogen) or an air pressure intensifier can be applied.
10912
12/11
Connection of the admission pressure
The admission pressure connection happens optionally via a P A-hose N 4 x 1 or with an expansion plug for N 6 x 1 to plug con-nection (9) (Prestolock), for PD 25 only via hose N 4 x 1.
T o protect the dead weight tester against impurities, an air control unit consisting of pressure regulator and filter (pores 10-20 µm with oil and water separator) has to be applied to the air control unit.The pressure regulator has to be limited to the maximum final value.
Refilling of the oil reservoir (3)
Examination of pressure gauges without external admission pressure – only model PD 6 –
If for PD 6 no admission pressure is available, the designated pres-sure can be produced with the helicoidal gear pump and change-over valve (7) as follows:
Close dosing valve "Vordruck" (8) (admission pressure).
Switch over the change-over valve "Spindelpumpe" (7) (helicoidal gear pump) to "Pumpe aus" (pump off).
Move the piston of the helicoidal gear pump (2) by left-turning of the star handle all the way to the stop.
Switch over the change-over valve (7) to "Pumpe ein" (pump on).Move the piston of the helicoidal gear pump by right-hand turning all the way up to the stop.
Switch over the change-over valve (7) to "Pumpe aus" (pump off). T urn the piston of the pump back all the way to the stop.Switch over to "Pumpe ein" (7) (pump on).
Please repeat this process as long as the designated pressure (max. 6 bar) is reached.Set of weights
ATTENTION ! Treat the set of weights carefully and avoid all kinds of damage! The set of weights are delivered in one wooden
box for models PD 6 and PD 10 and in two wooden boxes for model PD 25.
The instrument is being supplied in a filled condition.
Oil must be refilled immediately when the oil level is no longer visible
through the window of the oil clumn.
For refilling the change over valve (18) has to be switched to "Ent-lüften" ("vent"). Remove the screw (24) from the oil tank, fill in the oil up to the upper rim and close the reservoir by screwing in the screw (24).
Use only the oil included in shipment respectively reordered oil, which will be delivered upon request.
Advice
After approximately 40 operating hours the overflow oil of the system (via outlet 21) and the overflow oil of the measuring cylinder (via outlet 26) should be emptied in depressurised condition.
Examination of pressure gauges at connected admission pressure
All valves are closed.
operating without external pressure, compare below.)
The test item has to be screwed in densely into the clamping sleeve at the test connection (13).
Afterwards please open the pressure gauge valve "Prüfanschluss" (11) (test connection).
Place the spindle and pump approximately in the middle between front and back arrester, so that the pressure can be both, increased and decreased via the star handle of the spindle.
Put the weights according to the designated pressure on the base plate (14).
Switch the change-over valve (18) to "Vordruck" (admission pres-sure).
Open the dosing valve "Vordruck" (8) (admission pressure) slowly and reclose it.
Switch on the electric drive via the switch (22).
The pressure has to be adjusted via the star handle of the spindle so that the piston is placed in the measuring position (drawing 5a or 5b).
ATTENTION!
During measuring operation the piston neither may touch the lower nor the upper arrester.
Except of the 5 bar weight the weights can be laid down during ongoing operation.
The motor and the measuring system have to be stopped respectively switched off before laying down the 5 bar weights.
Please do also stop the motor before pressure relief.
The weights and the base plate [14 (basic load)] are marked with bar and kPa for the pressure, which is produced on the dead weight tester, as well as the instrument identification number and the final value.The base plate [14 (basic load)] without weights produces a pressure of 0.1 bar.
We recommend to work with additional weights to simplify the app-lying of further weights.
An additional weight is a weight as addition to the basic load 0.1 bar, to produce a pressure of 1 bar, respectively 5 bar.
First you apply an additional weight (0.9 or 4.9 bar) and then the next weights, according to the designated pressure.
In the lower range additional weight 0.9 bar is used and for above 5 bar (for PD 10 and PD 25) the additional weight 4.9 bar is used.The set of weights is composed as follows.PD 6
5 weights 1 weight 1 weight 4 weights 1 weight 4 weights PD 101 weight 1 weight 4 weights 1 weight 1 weight 4 weight 1 weight 4 weights PD 254 weights 1 weight 4 weights 1 weight 1 weight 4 weights 1 weight 4 weights
1 0.9 0.5 0.1 0.05 0.01 5 4.9 1 0.9 0.5 0.1 0.05 0.01 5 4.9 1 0.9 0.5 0.1 0.05 0.01
bar
bar (additional weight)bar bar bar bar
bar
bar (additional weight)bar
bar (additional weight)bar bar bar bar
bar
bar (additional weight)bar
bar (additional weight)bar bar bar bar
For pressure relief down to "0 bar" the admission pressure also has to be relieved by switching over the change-over valve (18) to "Entlüften" (ventilation) and opening the dosing valve "Vordruck" (admission pressure).
At operation of the change-over valves (7 + 18) please pay attention to a clear locking of the lever position above the nameplates.
1
The smallest graduation of the supplied set of weights is 0.01 bar.Correction weights for smaller graduations and for corrections of ambient parameter deviations of the standard conditions are avai-lable upon request.
Drawing 1Drawing 2
1 = Measuring system
2 = Helicoidal gear pump with star handle 3 = Oil reservoir 4 = Electrical motor
5 = Reading device (stationary pointer) 6 = Case Drawing 3 7 = for PD 6: change-over valve helicoidal gear pump ("Pumpe ein", "Pumpe aus", "Entlüften") (pump on, pump off, vent)
8 = Dosing valve "Vordruck" (admission pressure) 9 = "Eingang Vordruck" (inlet admission pressure)10 = "Entlüftung Vordruck" (ventilation admission pressure)
11 = Pressure gauge valve "Prüfanschluss" (test connection)
(only for PD 6! compare page 2)
12 = T est connection
13 = Clamping sleeve (SW 27)14 = Base plate (basic load)15 = Union nut
Drawing 5 a16 = Measuring piston
17 = Measuring cylinderReference edge of
(see drawing 3 for details of the Drawing 418 = Change-over valve for external the reading device for measuring system)
small weights admission pressure
("Vordruck", "Zu", "Entlüften") (admission pressure, closed, vent)19 = Machine mounts20 = Circular level
21 = "Ölablass" (oil drain port)Drawing 5 b (overflow of the system)
22 = Switch of the electrical motor
Reference edge of
23 = Calibration plate (for official verification)the reading device for 24 = Screw oil reservoirsmall weights25 = Nameplate
26 = "Ölablass Messzylinder"
(oil drain port measuring cylinder)
1