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RCM Products - Frequently Asked Questions

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Ordering & Specifying Grilles

RCM has been in the Air Distribution industry for many years and being familiar with many of our competitors and their products, we understand that due to the number of product options available, ordering and specifying products can be difficult due in part to complicated ordering codes.

So, we have tried to simplify the process by going back to basics.

Each product type has 3 letters corresponding to the individual product type i.e. LBG Linear Bar Grille, CFD Circular Floor Diffuser, FBL Fixed Blade Louvre etc.

Dependent on which type of product is specified, we then include additional codes for the option choices i.e. OB Opposed Blade Damper, RC Removable Core.

We decided to separate the Plenum Boxes, these also have multiple versions to choose from. Once again, these simplified are, PBL Plenum Box Lined, PBU Plenum Box Un-lined, options such as CS Cord Spigot Damper are available for plenums.

If, at any time you need assistance with the product codes, please do not hesitate to call our Sales Team and they will be pleased to help.

Selection Requirements

Air volume – l/s, m³/s or m³/h

Pressure drop – Pa

Noise – dB(A), NC or NR

Throw – m

Temperature difference

Application – Sidewall/ceiling

Ceiling heights

Room layout

Grille/Diffuser location

Grille/Diffuser type

Selection Guidelines

Max pressure drop for ceiling diffuser off FCU/VRV - 25-30Pa

Standard noise level for office environment - NC35

Air volume range for 4-Way Louvred Face - 20l/s - 350l/s

Air volume range for Perforated Diffuser - 20l/s - 200l/s

Air volume range for fixed Swirl Diffuser - 20l/s - 250l/s

Recommended air volume for Slot Diffuser - 30l/s/m per slot

Spigot velocities - 1.5m/s - 3m/s

Standard Temperature Differential - +/- 10k

Noise Level Guidelines

Studio’s, Concert Hall’s, Theatre’s. - NC20 / 25dB(A)

Private Bedrooms, Religious Buildings, Conference/Lecture Rooms - NC25 / 30dB(A)

Hospitals, Hotel Rooms, Libraries, Cinema’s - NC30 / 35dB(A)

General Offices, School’s, Restaurant’s - NC35 / 40dB(A)

Toilets, Office Reception’s, Corridor’s, Shop’s - NC40 / 45dB(A)

Kitchen’s, Computer Room’s, Cafe’s, Swimming Pool’s, Warehouse - NC45 / 50dB(A)

Diffuser Ceiling Types

TYPE S - STANDARD CUT IN

(Refer to product specific data sheet for dimensions)

TYPE-S

TYPE M - MODULAR TILE REPLACEMENT

TYPE-M

TYPE B - CLIP IN

(Note, clip in border for location purposes only. Recommend support by drop rods/plenum)

TYPE-B

TYPE T - TEGULAR TILE REPLACEMENT

(X, Y & Z Dimension to be advised by client)

TYPE-T

Plenum Box Spigot Velocity Chart

  Air Volume L/s
Spigot Area NR25-30 NR30 NR35 NR40
Dia 1.5m/s 2.0m/s 2.5m/s 3.0m/s 3.5m/s 4.0m/s
75 0.004 7 9 11 13 15 18
100 0.008 12 16 20 24 27 31
125 0.012 18 25 31 37 43 49
150 0.018 27 35 44 53 62 71
160 0.020 30 40 50 60 70 80
200 0.031 47 63 79 94 110 126
225 0.040 60 80 99 119 139 159
250 0.049 60 80 99 119 139 159
300 0.071 106 141 177 212 247 283
315 0.078 117 156 195 234 273 312
350 0.096 144 192 241 289 337 385
400 0.126 189 251 314 377 440 503
450 0.159 239 318 398 477 557 636
500 0.196 295 393 491 589 687 786
550 0.238 356 475 594 713 832 950
600 0.283 424 566 707 848 990 1131

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RCM Products
12-14 Sunbeam Road
Kempston
Bedford
MK42 7BY

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