PRA 91 (02)

About these operating instructions

• Warning! Read and understand all accompanying documentation, including but not limited to instructions, safety warnings, illustrations, and specifications provided with this product. Familiarize yourself with all the instructions, safety warnings, illustrations, specifications, components, and functions of the product before use. Failure to do so may result in electric shock, fire, and/or serious injury. Save all warnings and instructions for future reference.
  
• products are designed for professional users and only trained, authorized personnel are permitted to operate, service and maintain the products. This personnel must be specifically informed about the possible hazards. The product and its ancillary equipment can present hazards if used incorrectly by untrained personnel or if used not in accordance with the intended use.
  
• The accompanying documentation corresponds to the current state of the art at the time of printing. Please always check for the latest version on the product’s page on Hilti’s website. To do this, follow the link or scan the QR code in this documentation, marked with the symbol .
  
• Ensure that these operating instructions are with the product when it is given to other persons.
  

Explanation of symbols

Warnings

Symbols in the operating instructions

	Comply with the operating instructions
	Instructions for use and other useful information
	Dealing with recyclable materials
	Do not dispose of electric equipment and batteries as household waste
	Hilti Li‑ion battery
	Hilti charger

Symbols in illustrations

	These numbers refer to the illustrations at the beginning of these operating instructions.
	The numbers in illustrations refer to important work steps or to components important for the work steps. In the text, the corresponding numbers draw attention to these work steps or components, e.g. (3) .
	Item reference numbers are used in the overview illustration and refer to the numbers used in the key in the product overview section.
	This symbol is intended to draw your special attention to certain points for handling the product.

Product-dependent symbols

General symbols

Obligation symbols

Only use in enclosed spaces

General safety instructions, measuring tools

• Keep your workplace clean and well lit. Cluttered or poorly lit workplaces invite accidents.
  
• Do not operate the product in explosive atmospheres, such as in the presence of flammable liquids, gases or dust.
  
• Keep children and other persons clear when the product is in use.
  
• Use the product only within its specified limits.
  
• Comply with your national accident prevention regulations.
  

• Do not expose the product to rain or moisture. Penetrating moisture can cause short circuits, electrical shock, burns or explosions.
  
• Although the product is protected against the entry of moisture, it should be wiped dry before being put away in its transport container.
  

• Stay alert, watch what you are doing and use common sense when operating a measuring tool. Do not use a measuring tool while you are tired or under the influence of drugs, alcohol or medication. A moment of inattention while operating the measuring tool can result in serious personal injury.
  
• Avoid unusual body positions. Keep proper footing and balance at all times.
  
• Wear personal protective equipment. Wearing personal protective equipment reduces the risk of injury.
  
• Do not render safety devices ineffective and do not remove information and warning notices.
  
• Avoid accidental starting. Make sure that the measuring tool is switched off before connecting it to the battery and before picking it up or carrying it.
  
• Use the product and accessories in accordance with these instructions and in the way specified for this special type of tool. Take the working conditions and the work to be performed into account. Use of products for applications different from those intended could result in hazardous situations.
  
• Do not lull yourself into a false sense of security and do not flout the safety rules for measuring tools, even if you are familiar with the measuring tool after using it many times. Carelessness can result in serious injury within a fraction of a second.
  
• Do not use the measuring tool in the vicinity of medical devices.
  

• Use the product and accessories only when they are in perfect working order.
  
• Store measuring tools out of reach of children when not in use. Do not allow persons who are not familiar with the product or these instructions to operate it. Measuring tools are dangerous in the hands of inexperienced persons.
  
• Measuring tools need care and attention. Check that moving parts operate satisfactorily and do not jam, and make sure that no parts are broken or damaged in such a way that the measuring tool might no longer function correctly. Have damaged parts repaired before using the measuring tool. Many accidents are caused by poorly maintained measuring tools.
  
• Do not under any circumstances modify or tamper with the product. Changes or modifications not expressly approved by Hilti may restrict the user’s authorization to operate the product.
  
• Check the accuracy of the measuring tool before using it for important measurements, and if it has been dropped or subjected to other mechanical stresses.
  
• Due to the measuring principle employed, the results of measurements can be negatively affected by certain ambient conditions. These include, for example, the proximity of devices that produce strong magnetic or electro-magnetic fields, vibrations and temperature changes.
  
• Rapidly changing measuring conditions can falsify the results.
  
• When the product is brought into a warm environment from very cold conditions, or vice-versa, allow it to become acclimatized before use. Big differences in temperature can lead to incorrect operation and incorrect results.
  
• When adapters or accessories are used, make sure they are mounted securely.
  
• The measuring tool is designed for the tough conditions of jobsite use, but as with other optical and electrical products (e.g. binoculars, spectacles, cameras) it must be handled with care.
  
• The specified operating and storage temperatures must be observed.
  

Additional safety instructions

• Make sure that the product is set up on a flat, stable and vibration-free surface.
  
• Take care to ensure that no parts of the body are located under the tripod when the tripod is set up or in operation.
  
• Do not use the tripod as a hoist or lifting aid.
  
• When setting up the tripod indoors, check the subbase material. The tripod could scratch the subbase material.
  
• Always keep the threaded rod free from objects of any kind, including parts of the body or dirt.
  
• Do not put your fingers or other parts of the body into the tubes of the tripod legs or other points at which injuries could be caused.
  
• Only use the AC adapter for connecting to the power supply.
  
• Make sure that the product and the power supply unit do not present obstacles that could lead to a risk of tripping or personal injury.
  
• Do not touch the power supply unit if the power supply unit is damaged while work is in progress. Disconnect the supply cord plug from the power outlet.
  
• Avoid body contact with earthed or grounded objects such as pipes, radiators, kitchen ranges and refrigerators. There is an increased risk of electric shock if your body is grounded.
  
• Do not expose the supply cord to heat, oil or sharp edges.
  
• Never operate the AC adapter when it is dirty or wet. Dust (especially dust from conductive materials) or dampness adhering to the surface of the AC adapter may, under unfavorable conditions, lead to electric shock.
  
• Avoid touching the contacts of the power supply unit.
  
• Use the carry strap supplied with the tripod to make it easier to carry the PRA 91. When transporting the PRA 91, take care not to allow the tripod to cause injury either to yourself or to other persons. Particular care should be taken in checking the position of the points at the ends of the legs during transportation.
  
• Although the product is protected to prevent the ingress of moisture, you must always wipe the product dry before stowing it in a transport container.
  
• When you are finished using the PRA 91, always make sure that the threaded column is fully wound down before the tripod legs are folded together.
  
• Avoid short circuiting the battery terminals. Before inserting the battery into the product, check that the contacts of the battery and the contacts in the product are free of foreign matter. Short circuiting the battery terminals presents a risk of fire, explosion and chemical burns.
  
• For charging the battery, use only the PUA 81 power supply unit. Otherwise there is a risk of damaging the battery.
  

Electromagnetic compatibility

• The tool may cause interference to other devices (e.g. aircraft navigation equipment).
  
• The tool may be negatively affected by powerful electromagnetic radiation, possibly leading to incorrect operation.
  

Careful handling and use of batteries

• Comply with the following safety instructions for the safe handling and use of Li-ion batteries. Failure to comply can lead to skin irritation, severe corrosive injury, chemical burns, fire and/or explosion.
  
• Use only batteries that are in perfect working order.
  
• Treat batteries with care in order to avoid damage and prevent leakage of fluids that are extremely harmful to health!
  
• Do not under any circumstances modify or tamper with batteries!
  
• Do not disassemble, crush or incinerate batteries and do not subject them to temperatures over 80 °C (176 °F).
  
• Never use or charge a battery that has suffered an impact or been damaged in any other way. Check your batteries regularly for signs of damage.
  
• Never use recycled or repaired batteries.
  
• Never use the battery or a battery-operated power tool as a striking tool.
  
• Never expose batteries to the direct rays of the sun, elevated temperature, sparking, or open flame. This can lead to explosions.
  
• Do not touch the battery poles with your fingers, tools, jewelry, or other electrically conductive objects. This can damage the battery and also cause material damage and personal injury.
  
• Keep batteries away from rain, moisture and liquids. Penetrating moisture can cause short circuits, electric shock, burns, fire and explosions.
  
• Use only chargers and power tools approved for the specific battery type. Read and follow the relevant operating instructions.
  
• Do not use or store the battery in explosive environments.
  
• If the battery is too hot to touch, it may be defective. Put the battery in a place where it is clearly visible and where there is no risk of fire, at an adequate distance from flammable materials. Allow the battery to cool down. If it is still too hot to touch after an hour, the battery is faulty. Consult Hilti Service or read the document entitled "Instructions on safety and use for Hilti Li-ion batteries".
  
  Observe the special guidelines applicable to the transport, storage and use of lithium-ion batteries.
  Read the instructions on safety and use of Hilti Li-ion batteries that you can access by scanning the QR code at the end of these operating instructions.
  

Product overview

1. Rotating laser
   
2. Laser adapter 5/8"
   
3. Tripod head
   
4. Battery compartment
   
5. Extendable supports
   
6. Control panel
   
7. Charge state indicator
   
8. Arrow buttons, height adjuster
   
9. On/off button
   
10. LED display
    
11. AC adapter
    
12. Battery
    
13. LED, battery
    
14. Lock/release, battery
    

Intended use

• Use only the Hilti PRA 84 Li-ion battery for this product.
  
• For these batteries, use only the Hilti PUA 81 AC adapter.
  

Items supplied

Bluetooth

Automatic alignment

Charge state indicator

Technical data PRA 91

Technical data PRA 84

Technical data PUA 81

Inserting the battery

1. Push the battery into the holder on the automatic tripod.
   
2. Turn the latching mechanism clockwise until the locked symbol appears.
   

Removing the battery

1. Turn the latching mechanism counter-clockwise until the unlocked symbol appears.
   
2. Remove the battery from the product.
   

Charging the battery

1. Turn the latching mechanism of the battery until the charging connector on the battery is visible.
   
2. Plug the connection of the AC adapter into the battery.
   
3. Connect the power supply unit to the electricity supply.
   
   • The LED on the battery shows.
     
   • The battery is fully charged when the LED on the battery goes out.
     

Pairing automatic tripod and laser receiver

• Press the buttons on the automatic tripod and the laser receiver simultaneously for 3 seconds.
  
  • The laser receiver emits an acoustic signal.
    
  • The symbol appears on the display of the laser receiver
    
  • Both products switch off.
    

Installing rotating laser

• Screw the rotating laser clockwise on to the tripod head.
  

Switching on / off

1. Press the on/off button to switch the product on.
   
2. Press the on/off button again to switch the product off.
   

Aligning height of laser plane.

1. Install the rotating laser on the tripod head.
   
2. Now align the height of the laser plane manually or automatically.
   

Manual alignment

• On the automatic tripod, press the appropriate arrow buttons of the height adjuster to move laser plane up or down.
  

Automatic alignment

1. Press the button on the rotating laser, on the laser receiver and on the automatic tripod.
   
   • Successful connection both to the laser and to the automatic tripod is shown on the display of the laser receiver.
     
   • If connection cannot be established the symbol appears on the product concerned, indicating that no connection exists.
     
   • The rotating laser is leveling itself. The laser beam switches on and starts rotating as soon as the tool has leveled itself.
     
2. Keep the marking notch on the laser receiver at the height that is to be set. While this is in progress hold the laser receiver steady or secure it in place.
   
3. Begin automatic alignment by double-clicking the button on the laser receiver.
   
   • The automatic tripod moves up and down until the position is reached at which the laser plane is aligned with the marking notch of the laser receiver. A signal tone is emitted by the laser receiver repeatedly during this procedure.
     
   • The rotating laser levels itself once this position has been reached. Successful completion is indicated on the laser receiver by a continuous signal tone with a duration of 5 seconds. The symbol appears briefly on the display.
     
   • If automatic alignment cannot be completed successfully, the laser receiver emits short signal tones and briefly displays the symbol.
     
4. Check the height setting on the display of the laser receiver.
   
5. When automatic alignment has completed you can remove the laser receiver from the target plane and proceed, for example, to mark other points within the laser plane.