Hilti PRA25 User Manual

PRA25

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Bedienungsanleitung de
Operating instructions en

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It is essential that the operating instructions
are read before the tool is used the first
time.

Always keep these operating instructions
together with the tool.

Ensure that the operating instructions are
with the tool when it is given to other
persons.

PRA 25 laser detector

1. General information

1.1 Safety notices and their meaning

-CAUTION-

Draws attention to a potentially dangerous situation that
could lead to minor personal injury or damage to the
equipment or other property.

-NOTE-

Draws attention to instructions and other useful infor­mation.

1.2 Pictograms

Contents Page

1. General information 1

2. Description 2

3. Technical data 2

4. Safety precautions 2

5. Before use 3

6. Operation 4

7. Hilti calibration service 6

8. Care and maintenance 6

9. Disposal 7

10. Warranty 7

11. FCC statement 8

12. EC declaration of conformity 8

Component parts 

PRA 25 laser detector

 Control panel
 Audible signal emission aperture
 Detection area
 Display, front side (detailed illustration)
 Marking notch
 Reference plane
 Battery compartment cover
 Mounting thread
 Display, rear side
 On/off key
 Sensitivity selector key (standard or high

sensitivity)

 Audible signal selector key
 Direction adjustment key
 Manual/auto alignment key
 Line laser function key
 Rotation speed selector key
 Sensitivity indicator (standard or high)

 These numbers refer to the corresponding illustra­tions. The illustrations can be found on the fold-out cover
pages. Keep these pages open when studying the oper­ating instructions.
In these operating instructions, the PRA 25 laser detec­tor is referred to as “ the tool”.

Location of identification data on the tool

The type designation and serial number can be found
on the type plate on the tool. Make a note of this data in
your operating instructions and always refer to it when
making an enquiry to your Hilti representative or ser­vice department.

Type: PRA 25

Serial no.:

Warning signs

Read the operating

instructions before use.

Symbols

General
warning

 Indicator showing position of detector relative to

laser plane

 Line laser function indicator
 Beam catcher mode indicator

T

Rotation speed indicator

Z

Error indicator

U

Battery condition indicator

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2. Description

2.1 PRA 25 laser detector

The PRA 25 laser detector is designed to detect the laser
beam emitted by the PR 25 rotating laser and provide
remote control of its functions.

2.2 Features

The tool can be mounted on a measuring staff, telescopic
staff or, in conjunction with the appropriate holder, on
sight rails, wood lathes, frames etc.

3. Technical data

Operating range, detection
Operating range, remote control
Laser plane detection sensitivity (PR 25/10 m)

Audible signal
Liquid crystal display
Detection area
Center indicator, from top edge of housing
Marking notches (center)
Automatic cut-out
Dimensions
Weight
Power supply
Battery life at 20 °C (+68 °F)
Operating temperature
Storage temperature
Protection class
Mounting thread

Right of technical changes reserved.

2 to 200 m (6 to 650 ft); diameter
0 to 100 m (3 to 325 ft); diameter
High: ± 0.8 mm (0.03 inch);

Standard: ± 1.5 mm (0.06 inch)
2 volume levels or silent operation
On both sides
80 mm (3

1

/8inches)
50 mm (2 inches)
On both sides
After 30 min. when no laser beam is detected.
165

×67×

24 mm (6.5″×2.6″×0.9″inches)

0.2 kg (0.4 lbs) including batteries
2 x size AA batteries
Alkaline batteries: 30 hours
–20 °C to +50 °C (–4 °F to 122 °F)
–30 °C to +60 °C (–22 °F to 140 °F)
IP 56 (as per IEC 529)
M5 x 10 mm (0.4 inch)

Items supplied:

1 PRA 25 laser detector
1 PRA 25 operating instructions
1 PR 25/PRA 25 operating instructions
2 batteries (size AA)

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4. Safety precautions

4.1 Basic information concerning safety

In addition to the information relevant to safety given in
each of the sections of these operating instructions, the
following points must be strictly observed at all times.

● Tampering with or modification of the tool is not per-

missible.

● Observe the information printed in the operating instruc-

tions concerning operation, care and maintenance.

● Keep laser tools out of reach of children.

● Have the tool repaired only at a Hilti service centre.

● Take the surrounding conditions into account. Do not

use the tool where there is a risk of fire or explosion.

● Check the operating mode of the tool before each use.

4.2 Intended use

The tool is designed to be used in conjunction with the
PR 25 for determining, transferring or checking align­ment in the horizontal plane, inclined planes and right
angles, e.g.
– Transferring datum and height marks
– Marking out right angles for walls
– Vertical alignment with a reference point
– Setting out inclines

Hilti offers various accessories that allow the tool to be
used with maximum efficiency (please refer to the
PR 25 operating instructions).

4.3 Proper organization of the workplace

● Avoid unfavorable body positions when working on

ladders. Work from a stable stance and stay in bal­ance at all times.

● Measurements taken through panes of glass or other

objects may be inaccurate.

● Use the tool only within its specified limits.

4.4 Electromagnetic compatibility

Although the tool complies with the strict requirements
of the relevant directives, Hilti cannot entirely rule out
the following possibilities:

● The tool may cause interference to other equipment,

e.g. aircraft navigational equipment.

● The tool may be subject to interference caused by

powerful radiation, possibly leading to incorrect oper­ation. Check the readings for plausibility when mea­suring under these conditions or if you are unsure of
the results.

4.5 General safety precautions

● Check the tool before use. If the tool is found to be

damaged, have it repaired at a Hilti service center.

● The accuracy of the tool must be checked after it has

been dropped or subjected to other mechanical stress.

● If mounting on an adaptor, ensure that the tool is

screwed on securely.

● To avoid measurement errors, keep the optical sen-

sor area on the detector and the laser exit aperture on
the rotating laser clean.

● Although the tool is designed for the tough conditions

of jobsite use, as with other optical instruments (bin­oculars, spectacles, cameras) it should be treated with
care.

● Although the tool is designed to prevent entry of damp-

ness, it should be wiped dry each time before being
put away in its transport container.

● Check that your PRA 25 responds only to your PR 25

and not to other PR 25 lasers that may be in use on
the construction site (see “Pairing”).

4.6 Electrical

● Do not allow the batteries to fall into children's hands.

● Do not overheat or incinerate the batteries. They may

explode or release toxic substances.

● Do not attempt to recharge the batteries (non-recharge-

able, alkaline type).

● Do not solder the batteries into the tool.

● Do not discharge the batteries by short circuiting. This

may cause the batteries to overheat and swell up.

● Do not attempt to open the batteries and do not sub-

ject them to excessive mechanical stress.

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6. Operation

6.1 Working with the tool

The laser beam and the functions of the tool are indi­cated by visual and audible signals.

-NOTE-

The tool can be used either as a remote control unit or
as a laser detector. When using the tool as a laser detec­tor in conjunction with a measuring staff or telescopic
staff, check to ensure that it is attached securely.

6.1.1 Switching the tool on

Press the on/off key.

6.1.2 Setting the sensitivity

After switching on, the tool is set automatically to “Stan­dard” beam detection sensitivity. Sensitivity can be set
to “High” by pressing the sensitivity selector key.

6.1.3 Adjusting the audible signal volume

After switching on, the tool is set automatically to “Nor­mal” signal volume.
The volume can be set to “High” by pressing the signal
volume selector key and to “Off” by pressing the key a
second time.

6.1.4 Detecting the laser beam 

Hold the detector perpendicular to the plane of the rotat­ing laser beam. Detection of the beam is indicated by an
audible signal and visually by illumination of the center
display segment.

6.1.5 Catching the laser beam 

Hold the detector perpendicular to the plane of the rotat­ing laser where the beam can be detected. Press the line
laser key once to switch to beam-catching mode. This

is indicated in the display by the line laser symbol and
an additional arrow. The beam is then “caught” and
remains stationary at the PRA 25 as soon as the PR 25
has located its position.

6.1.6 Adjusting the speed of rotation

The speed of rotation can be adjusted by pressing the
rotation speed selector key.

– Press the key once to set rotation to medium speed.
– Press the key again to set rotation to high speed.
– Press the key once more to return to medium speed.
– Press the key yet again to set rotation to low speed.
– A further press of the key stops rotation.
– The next press of the key sets rotation to low speed.
– This procedure repeats itself.

6.1.7 Line laser function

After pressing the line function key, the PR 25 projects
a laser line. The line can be lengthened or shortened by
pressing the key again.

– Press the key once to project a short line.
– Press the key again to project a medium-length line.
– Press the key once more to project a long line.
– Press the key yet again to project an extra-long line.
– A further press of the key switches the tool back to the

long line.

– The next press of the key switches the tool back to the

medium-length line.
– Press the key once more to switch to a short line.
– Press the key again to project a laser spot.
– This procedure repeats itself.

6.1.8 Moving the laser line and spot

The laser line or laser spot can be moved to the left or
right by pressing the direction keys.
Holding down the direction keys increases the speed of
movement and the laser line or spot then move contin­uously.

5. Before use

-NOTE-

– The tool may be powered only by the batteries rec-

ommended by Hilti.

-CAUTION-

– Do not use damaged batteries.
– Do not mix old and new batteries. Do not mix batter-

ies of different types or batteries from various manu-

facturers.

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6.1.9 Automatic alignment 

A basic prerequisite for auto alignment is that the PR 25
is set up exactly according to instructions. The PR 25
must be set up so that the correct axis (X or Y) is posi­tioned in the direction in which alignment is to be per­formed. This can only be done in conjunction with the
PRA 25.

Procedure:

– Position the PR 25 at the reference point and with the

correct axis in the direction in which alignment is to
be performed (the operating range for auto alignment

is a radius of 5–50 m).
– Position the PRA 25 laser detector at the desired point.
– Check that no obstacles prevent communication between

the PR 25 and the PRA 25.
– Activate the auto alignment function by pressing the

X or Y key three times within one second. It is impor-

tant that the axes correspond correctly, i.e. when X (Y)

is to be aligned with the reference point, auto align-

ment of the X (Y) axis must be enabled by way of the

PRA 25.
– As long as the PR 25 is not in line laser mode, it then

switches automatically to medium rotation speed and

begins the search process. The auto align function is

indicated in the display by the axis currently being

aligned and by blinking arrows. An audible signal is

emitted continuously during the search process.
– The direction of the search process can be changed

by pressing the direction arrows.
– The beam moves to the zero point (reference plane)

as soon as the laser beam strikes the target area on

the PRA 25 detector.
– After reaching this point (finding the reference plane),

a signal sounds briefly indicating that the process is

complete. Only the axis that has been aligned is then

shown in the display.
If the process cannot be completed within a certain period

of time, an error is indicated in the display.

-NOTE- If an error is displayed

Please check that the PRA 25 is positioned within the
inclination range (+/–5°) and that no obstacles are located
between the rotating laser tool and the laser detector.

6.2. Manual alignment 

A basic prerequisite for manual alignment is that the
PR 25 is set up accurately. The PR 25 must be set up so
that the correct axis (X or Y) is positioned in the direc­tion in which alignment is to be performed.

Procedure:

– Position the PR 25 at the reference point and with the

correct axis in the direction in which alignment is to

be performed (the operating range for manual align-

ment is a radius of 5–50 m).

– Check that no obstacles prevent communication between

the PR 25 and the PRA 25.

– Activate the manual alignment function by pressing

the X or Y key twice within 1 second. It is important
that the axes correspond correctly, i.e. when X (Y) is
to be aligned with the reference point, auto alignment
of the X (Y) axis must be enabled by way of the
PRA 25.

– The laser beam can be moved to the desired position

by pressing the direction keys. Holding down the direc­tion keys increases the speed of movement and the
laser line or spot then move continuously.

– The manual alignment function is indicated in the dis-

play by the axis currently being aligned and by sta­tionary (constantly lit) arrows. An audible signal is also
emitted continuously during the search process.

– The system switches to normal operation when no key

is pressed within 5 seconds. Only the axis that has
been aligned is then indicated in the display.

6.2.1 Monitoring

The monitoring function checks to ensure that no dis­placement of the aligned plane has occurred (e.g. due
to vibration). If displacement has occurred, the laser
plane is realigned to the zero point (as long as it is still
within the detector target area). An additional laser detec­tor is required for working with the monitoring function.
A PRA 20 or PRA 25 may be used to detect the laser
beam.
As monitoring begins by way of the auto alignment
function, the PR 25 must be set up accurately. The
PR 25 must be set up so that the correct axis (X or Y)
is positioned in the direction in which alignment is to be
performed.

Procedure:

– Position the PR 25 at the reference point and with the

correct axis in the direction in which alignment is to
be performed (the operating range for auto alignment

is a radius of 5–50 m).
– Position the PRA 25 laser detector at the desired point.
– Check that no obstacles prevent communication between

the PR 25 and the PRA 25.
– Activation of this function requires the PRA 25 to be

switched off. While pressing and holding the X or Y

key (the key for the axis you wish to align), switch on

the laser detector by pressing the on/off key.
– The system is then in monitoring mode. The moni-

toring function is indicated in the display – the LEDs

for the axis to be aligned and the arrows blink alter-

nately.
– The auto alignment process then begins as previously

described.

6

– The auto alignment process stops as soon as the zero

point has been found. In contrast to full auto align­ment, no audible signal is emitted at the end of the
process.

– A check is carried out at regular intervals to ensure

that laser plane has not been displaced. If it is found
to have been displaced, the laser plane is again brought
into alignment with the zero point (as long as the laser
beam is still within the detector target area and line of
sight between the rotating laser and the detector has
not been interrupted for a long period).

-NOTE- If an error is displayed

Please check that the PRA 25 is positioned within the
operating range (within a 5–50 m radius, inclination
range +/– 5°). Check that the line of sight between the
two devices is not obstructed during the entire moni­toring period.

6.2.2 Pairing

It is possible to configure the PR 25 and the PRA 25 as
a pair. When the two devices are paired, the rotating laser
and the detector are assigned to each other. The rotat­ing laser then receives commands only from its “own”
detector/remote control unit. The devices can be paired
by pressing and holding down the on/off keys on both
devices simultaneously.

-NOTE-

The PR 25 and PRA 25 are not paired when supplied.
Each unpaired rotating laser receives commands from
any unpaired detector/remote control.

Pairing procedure:

– The devices can be paired by pressing and holding

down the on/off keys on the PR 25 and PRA 25 simul­taneously, as previously described, for more than
3 seconds. Successful pairing is confirmed by an audi­ble signal emitted by the PRA 25 and by the LEDs on
the PR 25 blinking twice.

Canceling pairing:

– Pairing can be cancelled by pressing and holding down

the on/off keys for more than 3 seconds. Cancellation
of pairing can only be successful when the on/off keys
on the PR 25 and PRA 25 are not pressed simultane­ously. Successful cancellation of pairing is confirmed
by the PRA 25 by the emission of an audible signal
and by the symbol “!” displayed. The PR 25 confirms
cancellation of pairing by causing all LEDs to blink.

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7. Hilti calibration service

We recommend that the tool is checked by the Hilti cal­ibration service at regular intervals in order to verify its
reliability in accordance with standards and legal require­ments. Use can be made of the Hilti calibration service
at any time, but checking at least once a year is recom­mended.
The calibration service provides confirmation that the
tool is in conformance, on the day it is tested, with the
specifications given in the operating instructions.

The tool will be re-adjusted if deviations from the manu­facturer's specification are found. After checking and
adjustment, a calibration sticker applied to the tool and
a calibration certificate provide written verification that
the tool operates in accordance with the manufacturer's
specification.
Calibration certificates are always required by compa­nies certified according to ISO 900x.
Your local Hilti Center or representative will be pleased
to provide further information.

7.1 Checking accuracy

Please refer to the PR 25 operating instructions.

8. Care and maintenance

8.1 Cleaning and drying

Use only a clean, soft cloth for cleaning. If necessary,
slightly moisten the cloth with pure alcohol or a little
water.

-NOTE-

● Do not use any other liquids as these may damage the

plastic parts.

● Observe the temperature limits when storing your

equipment. This is particularly important in winter or
summer, especially if the equipment is kept inside a
vehicle (storage temperatures: –30 °C to +60 °C/
–22 °F to +140 °F).

8.2 Storage

Remove the tool from its case if it has become wet. Clean
and dry the tool, its carrying case and accessories
(at max. temperature of 40 °C/108 °F). Re-pack the equip­ment only when it is completely dry.
Check the accuracy of the equipment before it is used
after a long period of storage or transportation.

8.3 Transportation

Use either the original Hilti cardboard box or packaging
of equivalent quality for transporting or shipping your
equipment.

-CAUTION-

Always remove the batteries before shipping the tool.

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9. Disposal

-CAUTION-

Improper disposal of the equipment may have serious consequences:

● The burning of plastic components generates toxic fumes which may present a health hazard.

● Batteries may explode if damaged or exposed to very high temperatures and thus cause poisoning, burns, acid

burns or environmental pollution.

● Careless disposal may permit unauthorized and improper use of the equipment, possibly leading to serious

personal injury, injury to third parties and pollution of the environment.

Most of the materials from which Hilti tools or appliances are manufactured can be recycled. The materials must
be properly separated before they can be recycled. In many countries, Hilti has already made arrangements for
taking back old tools and appliances for recycling. Ask Hilti Customer Service or your Hilti representative for fur­ther information.
Should you wish to return the tool or appliance yourself to a disposal facility for recycling, proceed as follows: Dis­mantle the equipment as far as is possible without need for special tools.

Separate the individual parts as follows:
Part/assembly

Housing
Control panel, display
Electronics
Batteries
Screws, small parts

* Dispose of batteries in accordance with national regulations.
Please help to protect our environment.

Main material

Plastic
Various
Various
Alkaline manganese
Steel

Recycling

Plastics recycling
Electronics scrap
Electronics scrap
*
Scrap metal

10. Warranty

Hilti warrants that the product supplied is free of defects
in material and workmanship. This warranty is valid as
long as the product is operated and handled correctly,
cleaned and serviced properly and in accordance with
the Hilti operating instructions, all warranty claims are
made within 12 months from the date of the sale (invoice
date), and the technical system is maintained. This means
that only genuine Hilti consumables, components and
spare parts may be used with the product.

This warranty provides the free-of-charge repair or replace­ment of defective parts only. Parts requiring repair or
replacement as a result of normal wear and tear are not
covered by this warranty.

Additional claims are excluded, unless stringent national
rules prohibit such exclusion. In particular, Hilti is not
obligated for direct, indirect, incidental or consequential
damages, losses or expenses in connection with, or
by reason of, the use of, or inability to use the product
for any purpose. Implied warranties of merchantabil­ity or fitness for a particular purpose are specifically
excluded.

Send the product and/or related parts immediately upon
discovery of the defect to the applicable Hilti marketing
organization for repair or replacement.

This constitutes Hilti's entire obligation with regard to
warranty and supersedes all prior or contemporaneous
comments and oral or written agreements concerning
warranties.

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This device complies with Part 15 of the FCC Rules and
RSS-210 of IC. Operation is subject to the following two
conditions:

(1) this device may not cause harmful interference, and
(2) this device must accept any interference received,

including interference that may cause undesired
operation.

Information plates on the product:

-CAUTION-

This equipment has been tested and found to comply
with the limits for a class B digital device, pursuant to
part 15 of the FCC rules.These limits are designed to
provide reasonable protection against harmful interfer­ence in a residential installation. This equipment gener­ates, uses, and can radiate radio frequency energy and,
if not installed and used in accordance with the instruc­tions, may cause harmful interference to radio com­munications.
However, there is no guarantee that interference will not
occur in a particular installation.
If this equipment does cause harmful interference to
radio or television reception, which can be determined
by turning the equipment on and off, the user is encour­aged to try to correct the interference by one or more of
the following measures:

● Re-orient or re-locate the receiving antenna.

● Increase the distance between the equipment and

receiver.

● Consult the dealer or an experienced TV/radio tech-

nician for assistance.

(Requested by FCC §15.21): Changes or modifications
not expressly approved by Hilti could restrict the user's
right to operate the equipment.

11. FCC statement (applicable in US) / IC statement (applicable in Canada)

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12. EC conformity

In conformance with CE

We declare, on our own responsibility, that this product
complies with the following directives and standards:
EN 300 440-2, EN 301 489-3 V1.4.1,
EN 60950-1:2001/IEC 60950-1:2001

Designation: Laser detector
Type: PRA 25
Year of design: 2004

Hilti Corporation

Matthias Gillner Dr. Heinz-Joachim Schneider

Head BU Measuring Systems Executive Vice President
01 /2005 BA Electric Tools & Accessories

01 /2005

Hilti Corporation

FL-9494 Schaan
Tel.: [phone]
Fax: [phone]
www.hilti.com

Hilti = registered trademark of Hilti Corp., Schaan W 3048 1004 10-Pos. 1 1 Printed in Liechtenstein © 2004
Right of technical and programme changes reserved S. E. & O.

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