
PLM - Plenum box

Plenum for linear slot diffuser
Plenum for Halton SLM diffuser
- Plenum for connecting Halton SLM linear slot diffuser supply/exhaust unit to ductwork
- Ensures proper function of the supply air diffuser
- Access for ductwork cleaning
Product Models and Accessories
- Model with sound attenuation, mineral wool or polyester fibre
- Detachable airflow rate measurement and balancing module
The plenum is made of galvanised steel.
The plenum comprises an airflow measurement and adjustment module.
The diffuser is detachable in order to provide access to the measurement and adjustment module in the plenum.
The plenum comprises sound attenuation material made of mineral wool or polyester fibre.
The plenum reduces duct pressure and air velocity in order to supply air throughout the entire face area of the linear diffuser and improve the air distribution quality.
Halton PLM
Plenum for Halton SLM linear slot diffuser
- Plenum for connecting Halton SLM linear slot diffuser supply/exhaust unit to ductwork
- Ensures proper function of the supply air diffuser
- Access for ductwork cleaning
Product Models and Accessories
- Model with sound attenuation, mineral wool or polyester fibre
- Detachable airflow rate measurement and balancing module
Dimensions ▲
Slots | H | K | K1 | ØD |
1 | 235 | 130 | 59 | 160 |
2 | 275 | 181 | 110 | 200 |
3 | 275 | 232 | 161 | 200 |
4 | 325 | 283 | 212 | 250 |
Standard dimensions for Halton SLM+PLM
Diffuser active length (mm) | 572 | 872 | 1172 | 1472 | 1772 |
L (mm) | 571 | 871 | 1171 | 1471 | 1771 |
L1 (mm) | 286 | 436 | 586 | 368 | 443 |
Duct connections (pcs) | 1 | 1 | 1 | 2 | 2 |
In addition to standard linear slot diffuser sizes, other sizes can be ordered.
The maximum length is 2000 mm.
Continuous plenums with modular design are also available for installation lengths greater than 2000 mm.
Material ▲
Part | Material | Note |
Plenum box / spigot | Galvanised steel | Spigot equipped with rubber gasket |
Sound attenuation material | Mineral wool or polyester fibre | The mineral wool is fixed with nails |
Accessories ▲
Accessory | Code | Descritption |
Sound attenuation material | 2W | Mineral wool on 2 sides |
Sound attenuation material | 5W | Mineral wool on 5 sides |
Sound attenuation material | 2P | Polyester fibre on 2 sides |
Sound attenuation material | 5P | Polyester fibre on 5 sides |
Airflow measurement and adjustment unit | OM | For supply installation |
Function ▲
The duct pressure and air velocity are reduced inside the Halton PLM plenum box.
Air is supplied into the space through the diffuser, improving the air distribution quality.
The airflow rate can be adjusted using the optional measurement and adjustment module MSM.
Installation ▲
Key:
1. Plenum box
2. Measurement and adjustment module (MSM)
The Halton PLM is installed into the suspended ceiling with M8 drop rods (not supplied in the delivery) and connected to the ductwork with a spigot equipped with an integral rubber gasket.
When equipped with a measurement and adjustment module, the recommended safety distance upstream of the device is at least 3D, in order to ensure a reliable airflow rate measurement.
The units control spindle must not be excessively bent.
Adjustment ▲
In order to enable airflow adjustment and measurement of airflow rate, it is recommended that the diffuser be connected to the plenum equipped with the MSM module.
The supply flow rate is determined by using the measurement and adjustment module MSM.
Detach the diffuser and pass the tubes and control spindle through the diffuser.
Replace the diffuser.
Measure the differential pressure using a manometer. The flow rate is calculated using the formula below:
∆pm Measured pressure [Pa]
k The factor given as a function of mounting and diameter
qv Airflow rate [l/s]
The k-factor for installations with different safety distances
(D= duct diameter):
PLM | > 6xD | min. 3xD |
160 | 19 | 22 |
200 | 49 | 32 |
250 | 51 | 51 |
Adjust the airflow rate by rotating the control spindle until the desired setting is achieved.
Lock the damper position with a screw.
Replace the tubes and spindle into the plenum and replace the diffuser.
Servicing ▲
Remove the measurement and adjustment module by gently pulling the shaft; (not the control spindle).
Wipe the parts with a damp cloth, instead of immersing in water.
Reassemble the measurement and adjustment module by pushing the shaft back into place until the module meets the stopper.
Specification ▲
The plenum is made of galvanised steel.
The plenum comprises an airflow measurement and adjustment module.
The diffuser is detachable in order to provide access to the measurement and adjustment module in the plenum.
The plenum comprises sound attenuation material made of mineral wool or polyester fibre.
The plenum reduces duct pressure and air velocity in order to supply air throughout the entire face area of the linear diffuser and improve the air distribution quality.
Order Code ▲
PLM/S-L-D-N; IN-OM-ZT
S = Number of slots
1, 2, 3, 4
L = Length
372, +1, .., 50000
D = Diameter of duct connection
160, 200, 250
N = Number of duct connections
1, +1, .., ((L-30)/(D+30)1)
Other Options and Accessories
IN = Sound attenuation material
N No attenuation material
2W Mineral wool on 2 sides
5W Mineral wool on 5 sides
2P Polyester fibre on 2 sides
5P Polyester fibre on 5 sides
OM = Measurement/adjustment module MSM
N No measurement or adjustment module
Y MSM installed in each duct connection
ZT = Tailored product
N No
Y Yes
Code example
PLM/1-400-160-1, IN=N, OM=N, ZT=N
Downloads & Media
Halton PLM - fi | Type Datasheet | Language Finnish (Finland) | Size 424.3 kB |
Halton PLM - se | Type Datasheet | Language Swedish (Sweden) | Size 425.8 kB |
Halton PLM - ru | Type Datasheet | Language Russian (Russia) | Size 446.2 kB |
Halton PLM - gb | Type Datasheet | Language English (United Kingdom) | Size 424.3 kB |
Halton PLM - nl | Type Datasheet | Language Dutch (Netherlands) | Size 424.9 kB |
Halton PLM-PMM - fr | Type Datasheet | Language French (France) | Size 1.1 MB |