
MICROFAST®
QUICK RESPONSE
PENDENT SPRINKLER
VK331 (K4.2)
TECHNICAL DATA
Page 4 of 5
Form No. F_061814 21.03.05 Rev 21.1
The Viking Corporation, 210 N Industrial Park Drive, Hastings MI 49058
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Approval Chart 1 (UL)
The Viking Microfast® Quick Response Pendent
Sprinkler VK331
Maximum 175 PSI (12 Bar) WWP
Base
Part
Number1
SIN Sprinkler
Style
Thread Size Nominal K-Factor Overall Length Listings and Approvals3
(Refer also to Design Criteria.)
NPT BSPT U.S. metric2Inches mm cULus4VdS LPCB
21271 VK331 Pendent 1/2” 15 mm 4.2 57 2-1/4 58 A1X, B1Y, C2X, D2Z -- -- --
Approved Temperature Ratings
A - 135 °F (57 °C), 155 °F (68 °C), 175 °F (79
°C), 200 °F (93 °C), 286 °F (141 °C)
B - 135 °F (57 °C), 155 °F (68 °C), 175 °F (79
°C), and 200 °F (93 °C)
C - 155 °F (68 °C), 175 °F (79 °C), 200 °F (93
°C), 286 °F (141 °C)
D - 155 °F (68 °C), 175 °F (79 °C), and 200 °F
(93 °C)
Approved Finishes
1 - Brass, Chrome, White Polyes-
ter5,6, and Black Polyester5,6
2 - ENT5
Approved Escutcheons
X - Standard surface-mounted escutcheon
Y - Standard surface-mounted escutcheon or recessed with
the Viking Micromatic®Model E-1, E-2, or E-3 Recessed
Escutcheon
Z - Standard surface-mounted escutcheon or recessed with
the Viking Micromatic®Model E-1 Recessed Escutcheon
Footnotes
1Base part number shown. For complete part number, refer to Viking’s current price schedule.
2Metric K-factor measurement shown is when pressure is measured in Bar. When pressure is measured in kPa, divide the metric K-factor shown by
10.0.
3This table shows the listings and approvals available at the time of printing. Other approvals may be in process.
4Listed by Underwriters Laboratories Inc. for use in the U.S. and Canada.
5cULus Listed as corrosion-resistant.
6Other colors are available on request with the same Listings and Approvals as the standard colors.
DESIGN CRITERIA - UL
(Also refer to Approval Chart 1 above.)
cULus Listing Requirements:
The Viking Microfast®Quick Response Pendent Sprinkler VK331 is cULus Listed as indicated in the Approval Chart for installation in
accordance with the latest edition of NFPA 13 for standard spray sprinklers.
• Small orifice sprinklers are limited to Light Hazard where allowed by the installation standards being applied, with hydraulically
calculated wet systems only. Exception: 4.2K sprinklers may be installed on hydraulically calculated dry pipe systems where
piping is corrosion resistant or internally galvanized
• The sprinkler installation rules contained in NFPA 13 for standard spray pendent sprinklers must be followed.
IMPORTANT: Always refer to Bulletin Form No. F_091699 - Care and Handling of Sprinklers. Also refer to Form No. F_080614
for general care, installation, and maintenance information. Viking sprinklers are to be installed in accordance with the latest
edition of Viking technical data, the appropriate standards of NFPA, LPCB, APSAD, VdS or other similar organizations, and
also with the provisions of governmental codes, ordinances, and standards, whenever applicable.