Our expert responds #18

QUESTION
I have some doubts about how to anchor the fire-fighting pressurisation units. Could you please explain to me what the new edition of UNI 11292 says about this?

ANSWER
The new edition of UNI 11292 entered into force on 14 February 2020. Point 6.6 of the standard clarifies how the anchoring of the pumping units (PUMP-SET) must be carried out.

6.6 ANCHORING SYSTEMS

The room must have a supporting surface (foundation) of the pumping unit capable of ensuring adequate resistance to the static and dynamic loads of the unit itself.

In order to avoid the transmission of vibrations to the structures of the room, suitable anchoring or bonding systems must be provided on the ground of the pumping unit (see Figure 3). The anchoring system must ensure the stability and alignment of the pumping unit over time and have mechanical characteristics so as to withstand the vibration of the unit during its operation.

Installations in areas with seismic characteristics must be carefully evaluated.

Loads on the pump flanges must also be avoided by installing suitable supports.

Given that each individual pumping unit (PUMP-SET) must be anchored independently to the support surface, and that the definition of PUMPING UNIT = PUMP SET: is shown in point 3.15 of the standard (see also #17 of our section THE EXPERT RESPONDS)

3.15      Pump set: unit comprising a pump with its motor and coupling system, any base and command and control panel

we have that:

• each individual PUMP-SET must be individually anchored to the support surface
• the anchoring must take place by means of dowels directly anchored in the concrete (see figure)
• the pumping units must not transmit vibrations to the structures of the room

it follows that:

• it is not possible to use floating sheet metal floors, supported by metal profiles that are directly connected to the structure of the room
• it is not possible to use compact pressurisation units, in which the individual PUMP-SETs are mounted on an additional common base which in turn is anchored to the ground
• anti-vibration devices cannot be used under the frames of the individual PUMP-SETS
• ONLY PUMP-SETS THAT ARE INDEPENDENT OF EACH OTHER, ARE INDEPENDENTLY ANCHORED TO THE CONCRETE SUPPORT SURFACE AND THAT COMPLY WITH THE DISTANCES REQUIRED BY THE STANDARD CAN BE COMMISSIONED (see also #05 of our section THE EXPERT RESPONDS)

The following images show some examples of systems to be avoided and of systems that instead respond to the requirements of the standard

EXAMPLE OF ANCHORING OF THE PUMP-SETS ON A FLOATING FLOOR RESTING ON METAL PROFILES

THIS TYPE OF ANCHORING IS NOT ALLOWED

EXAMPLE OF ANCHORING WITH ANTI-VIBRATION.  THE USE OF THE ANTI-VIBRATION DEVICE IS NOT ALLOWED

EXAMPLE OF CORRECT ANCHORING OF THE PUMP-SET TO THE CONCRETE SUPPORT SURFACE AS REQUIRED BY UNI 11292:2019