#247 – XT1 Fire Sprinklers and Accessories: The “Next Generation” of Viking Sprinklers

Ease of installation and reliability figure prominently in Viking’s XT1 fire sprinkler heads, wrenches, head guards, and water shields

It’s been less than a year since Viking announced the release of its XT1 fire sprinkler heads and accessories—a product line the company says has “re-thought and re-invented the fire sprinkler from the ground up.” But what do the new Viking fire sprinklers, head guards, escutcheons, and water shields offer that their predecessors don’t?

In this article, we look at the XT1 sprinkler platform, covering product design, cross-compatibility between old and new products, and purchasing and identification tips.

If you’d like, you can also browse our selection of upright and pendent XT1 sprinklers.

The XT1 improves upon the corrosion-resistance, ease of installation, and aesthetic benefits of earlier Viking fire sprinkler heads

Viking heralds the XT1 as a “‘next generation’ sprinkler platform.” That platform—which includes new sprinkler heads, head guards, water shields, and specialty wrenches—is the next step in an evolution spanning roughly four decades. The Viking Model M fire sprinklers of the 1980s were replaced by the small-frame sprinklers of the 2000s, which are now being replaced by XT1 heads.

Specifications for the original Model M are hard to come by, but the trend is toward smaller fire sprinkler heads. The VK3001, which replaces the 2 3/16” tall VK300, is only 1 15/16” tall—making it ten percent shorter than its predecessor.

Evolution of Viking fire sprinklers
From left to right: a Model M and Viking Microfast® head—both VK300—and the XT1-series VK3001 (scale not exact). Left image source: eBay

XT1 fire sprinkler heads improve on the small-frame sprinklers they replace in four critical ways:

  • Enhanced corrosion resistance. Deflectors consist of stainless steel instead of the brass or copper used previously. Further, the spring and seal assembly within each head is protected by a polytetrafluoroethylene (PTFE) seal.
  • Greater reliability. Each XT1 has a pip cap assembly—the plug that ejects from a fire sprinkler head when it activates—with “an integral anti-lodgment device.” Basically, a hinge on the frame stops the plug (and other parts) from catching on the deflector as they fall.
  • Aesthetic enhancements. The deflector is laser-etched rather than stamped or engraved, making identification marks easier to read. Further, the metal frame is smoother, resulting in a more even finish.
Viking sprinkler finish comparison
Note how the even white finish on the VK1021—the pendent XT1 head on the right—compares to its predecessor, the VK102.

A small but carefully chosen line of new fire sprinkler heads smooths the transition to the XT1 platform

Currently, Viking offers twelve XT1 heads, including six upright models listed for use on vacuum fire sprinkler systems. That selection features the most common thread types—1/2” and 3/4” National Pipe Thread (NPT)—and standard temperatures between 135 and 286 degrees Fahrenheit (57 to 141 degrees Celsius). Each has a pressure rating of 175 PSI, with higher-pressure XT1 models slated for release at a date to be determined. And while XT1 sprinklers are now Viking’s default model, the Microfast frames they replace can still be ordered upon request.

While they’re available with K-factors (orifice sizes) of 5.6 and 8.0, Viking’s line of 8.0K XT1 sprinklers with 1/2” thread connections aren’t listed for use in new NFPA 13 installations.

The reason has little to do with Viking: any 1/2” sprinklers with a K-factor greater than 5.6K may not be installed in new sprinkler systems that comply with NFPA 13: Standard for the Installation of Sprinkler Systems (for more, see section 9.4.5 in the 2019 edition). However, Viking’s 3/4” XT1 sprinklers with 8.0K orifices CAN be used on both new construction and retrofits.

Unlike the previous Micromatic or Model M sprinklers that had five-digit sprinkler identification numbers (SIN), XT1 heads feature a six-digit SIN. The new sprinklers’ SIN numbers bear a close relationship to their predecessors: in each case, a “1” or “2” is added to the old model’s five-digit SIN.

Thus, a VK102 is replaced by a VK1021, a VK202 by a VK2021, and so on. So far, only models with an 8.0K orifice and a 1/2” thread size—the “retrofit-only” models—have SINs suffixed with a 2.

For readers’ convenience, the new sprinklers’ SINs and base part numbers—along with SINs and part numbers for old models—are listed in the table below (updated August 2019).

Viking XT1 – Pendent Heads (August 2019)

Old SIN Old Part Number Connection Response Type Orifice New SIN New Part Number
VK102 12986, 10139 1/2″ SR 5.6K VK1021 19915
VK202 18264, 10142 3/4″ SR 8.0K VK2021 19923
VK202 18269, 10223 1/2″ SR 8.0K VK2022 19919
VK302 12979, 6662 1/2″ QR 5.6K VK3021 19917
VK352 18258, 6666 3/4″ QR 8.0K VK3521 19925
VK352 18260, 6765 1/2″ QR 8.0K VK3522 19921


Viking XT1 – Upright Heads (August 2019)

Old SIN Old Part Number Connection Response Type Orifice New SIN New Part Number
VK100 12986, 10138 1/2″ SR 5.6K VK1001 19914
VK200 18263, 10141 3/4″ SR 8.0K VK2001 19922
VK200 18268, 10220 1/2″ SR 8.0K VK2002 19918
VK300 12978, 6661 1/2″ QR 5.6K VK3001 19916
VK350 18257, 6665 3/4″ QR 8.0K VK3501 19924
VK350 18259, 6764 1/2″ QR 8.0K VK3502 19920

Update: Since the XT1 release, Viking has updated these sprinklers with new models that allow for easier installation. To learn about the change and why it was made, read this blog. To convert some of the above part numbers to the latest, equivalent model, reference this table:

SIN Old Part Number New Part Number Type K-Factor Shop the QRFS Catalog
VK1001 19914 23867 Upright 5.6 Brass 155F |
Brass 200F |
Brass 286F
VK1021 19915 23868 Pendent 5.6 Brass 155F |
Brass 200F |
Brass 286F |
Chrome 155FChrome 200F |
Chrome 286F |
White 155F
VK2001 19922 23876 Pendent 8.0 Brass 155F |
Brass 200F |
Brass 286F
VK2021 19923 23875 Upright 8.0 Brass 155F |
Brass 200F |
Brass 286F
Chrome 155FChrome 200F |
Chrome 286F |
White 155F
VK3001 19916 23869 Upright 5.6 Brass 155F |
Brass 175F |
Brass 200F |
Brass 286F
VK3021 19917 23870 Pendent 5.6 Brass 155F |
Brass 200F |
Brass 286F
Chrome 155FChrome 175F |
Chrome 200F |
Chrome 286F |
White 155F

White 175F |
White 200F |
White 286F

VK3501 19924 23877 Upright 8.0 Brass 155F |
Brass 200F |
Brass 286F
VK3521 19925 23878 Pendent 8.0 Brass 155F |
Brass 200F |
Brass 286FChrome 155F |
White 155F

Viking’s standard part number format encodes finishes and temperatures of XT1 fire sprinklers for easier ordering

All of Viking’s XT1 fire sprinkler heads are listed for use with the following finishes:

  • Brass
  • Chrome
  • White Polyester
  • Black Polyester

Additionally, these heads may be ordered with a corrosion-resistant ENT plating (otherwise known as electroless-nickel-plated PTFE). PTFE, or polytetrafluoroethylene, resists chemical changes, making it a particularly suitable exterior for sprinklers in harsh environments. Each ENT-plated model has passed a 30-day corrosion test in accordance with UL 199, in which sprinkler performance is tested after 30 days of exposure to salt fog and other forms of moist, corrosive air.

ENT finish on a Viking sprinkler
ENT plating—which leaves a finish like the one shown here—is Viking’s most corrosion-resistant option for XT1 sprinkler heads. Source: Viking Group Inc

Viking identifies these finishes—and the sprinkler’s activation temperature—with short suffixes added to their five-digit part numbers. The first part of the suffix indicates the finish:

  • Brass: 00000A_
  • Chrome: 00000F_
  • White: 00000M_/W
  • Black: 00000M_/B
  • ENT: 00000N_

The second part of the suffix, which fills in the blanks above, refers to the sprinkler’s activation temperature:

  • 135F (57C): 00000_A
  • 155F (68C): 00000_B
  • 175F (79C): 00000_D
  • 200F (93C): 00000_E
  • 286F (141C): 00000_G
  • Open (No Temperature): 00000_Z

The table below shows how these suffixes are applied to a specific XT1 fire sprinkler head: the VK3021, or Viking part number 19916:

Sample Part Numbers for Viking VK3021 (Formerly VK302) Fire Sprinkler Heads by Finish and Temperature

Temperature Finish
Brass Chrome White Black ENT
135F (57C) 19917AA 19917FA 19917MA/W 19917MA/B 19917JNA
155F (68C) 19917AB 19917FB 19917MB/W 19917MB/B 19917JNB
175F (79C) 19917AD 19917FD 19917MD/W 19917MD/B 19917JND
200F (93C) 19917AE 19917FE 19917ME/W 19917ME/B 19917JNE
286F (141C) 19917AG 19917FG 19917MG/W 19917MG/B 19917JNG
Open 19917AZ 19917FZ 19917MZ/W 19917MZ/B 19917JNZ

New wrenches expedite installation of XT1 heads in a variety of situations

Fire sprinkler contractors transitioning to XT1 fire sprinklers will need at least one new wrench—and possibly a few others. Wrenches for small-frame Micromatic heads don’t fit the smaller frames found on newer models. In most cases, one standard wrench can install all XT1 sprinklers, whether they’re installed with recessed escutcheons or not.

In total, four wrenches—each designed to prevent damage to sprinkler heads—are available in the XT1 platform:

  • The Installer Wrench. Also called a standard wrench, this model has an offset handle and can install any XT1 sprinkler in any escutcheon. But it’s best used for pendent sprinklers with flush or semi-recessed escutcheons. While it can be used to install upright sprinklers water shields, the standard wrench shouldn’t be used to install XT1 heads with Viking-brand head guards or pendent models with Viking’s water shields.
  • The Straight Wrench is designed for use with upright XT1 sprinklers. While the offset in the standard wrench can follow the contours of a recessed or semi-recessed escutcheon, straight wrenches allow for more direct engagement with sprinklers that don’t have an escutcheon.
  • The Recessed Socket Wrench, which can streamline installation of pendent heads with recessed escutcheons.
  • The XT1 Guard Wrench fits sprinklers with Viking-brand head guards—including pendent heads that use a hybrid head guard and water shield.

For a visual take on the differences between these wrenches, check out this video from Viking:

Escutcheons, head guards, and water shields round out the XT1 platform

NP-type escutcheons replace Model-E-types

Three new escutcheons are listed for use with XT1 fire sprinkler heads: the NP-1, NP-2, and NP-3. Unfortunately, the Model E escutcheons—used with Model M and small frame sprinklers—aren’t. For recessed applications, installers will need to choose between one of Viking’s NP-type escutcheons.

The NP-1 escutcheon offers the greatest possible recess—as much as 5/8”. The outside diameter of the outer cup is equivalent to the slip-on model E-1, with 3 1/16” available to cover openings as small as 2 5/16” and as large as 2 1/2”.

The NP-2 escutcheon has a slightly smaller maximum recess—only 1/2”—but allows the sprinkler to extend an additional 11/32” away from the ceiling. The NP-2 has a marginally larger outside diameter and can cover the same hole sizes as the NP-1.

The NP-3 escutcheon offers the same benefits as the NP-2 with one tweak: the outside diameter is substantially larger at 5 1/8.” Consequently, the NP-3 can be installed in seismic applications where clearance around sprinkler heads is required. The NP-3 meets requirements from the American Society of Civil Engineers (ASCE) for category C, D, and E structures, which cover a variety of buildings subject to moderate or severe shaking.

For more on fire sprinklers and seismic concerns, check out “Guide to Flexible Fire Sprinkler Drops, Part 1: Ceilings, Sprinkler Armovers, and Seismic Issues.

Low-profile head guards require special tools and attentive installation

For sprinklers in accident- or damage-prone areas, the XT1 platform includes head guards. At 2 15/16” wide and 2 3/16” tall, Viking’s Model XG Sprinkler Guard protects sprinklers while adding less than an inch to overall height.

The Model XG guards require two tools to install: Viking’s XT1 Sprinkler Guard Wrench—which includes slots that slide around the head guard—and a T15 Torx screwdriver (for indentations shaped like a six-pointed star). These guards are seated and locked on the sprinkler before threading the head into the pipes.

Because these guards fit snugly around XT1 fire sprinkler heads, installation requires special care. Contractors must:

  • Mind the angle of the sprinkler. Pendent and upright sprinklers insert at slightly different angles. Pendent heads insert with both the head and the guard upright, while upright heads enter at roughly a 30-degree offset.
  • Orient the sprinkler carefully. XT1 sprinklers use a hinge to direct the plug away from the deflector when the sprinkler activates. Installing the head in the guard at the wrong angle can pinch the hinge between the frame and the guard, which could trap the plug in the water’s path.
Hinge on an XT1 Viking fire sprinkler XT1
Pinching this hinge against an XG Sprinkler Guard can cause the head to malfunction.

Water shields mount on head guards or the sprinkler’s frame to ensure timely activation of XT1 heads

Pairing an XT1 sprinkler with one of Viking’s two water shields converts the sprinkler head to an intermediate rack-storage sprinkler. While storage isn’t the only application for these guards—which can double as a weather shield—their primary use is to ensure that heat-activated parts on closely spaced heads don’t get cooled by water spray.

Viking offers two cold-rolled steel water shields for XT1 sprinklers:

  • The XWU Water Shield, which sits on top of an XG Sprinkler Guard to protect pendent heads
  • The F-1 Water Shield, which sits at the base of an upright XT1 head and may or may not be paired with an XG guard

Both water shields can be secured without additional tools. The XWU Water Shield, which resembles a pet cone, clips directly to the frame of an XG guard. An F-1 water shield slides over the sprinkler’s threads, resting on the base of the frame.

Two caveats are worth noting: first, the XWU water shield should not be used with recessed escutcheons. The guard may not seat correctly. Second, use the XT1 Guard Wrench—not any of the other three wrenches—when installing an XWU water shield. The wire from Viking’s head guards, which are used with every Model XWU shield, will prevent other wrenches from getting a proper grip.

Installers and consumers will reap the rewards of Viking’s improvements

Whether Viking has reinvented the fire sprinkler or simply improved it is a question we’ll leave to installers. For now, it’s safe to say that the XT1’s compact frames, aesthetic improvements, and varied accessories should benefit installers and those who live with fire sprinklers.

If you’d like to get your hands on some of Viking’s newest products, check out QRFS’s selection of more than 40 XT1 fire sprinkler heads. With pendent and upright heads in chrome, white, and brass—ranging from 155 to 286 degrees Fahrenheit—these UL-listed and FM-approved heads are ready for use in tight spaces, hot and corrosive environments, and aesthetically pleasing spaces.

A quick-response VK3021 Viking sprinkler
This quick-response VK3021 pendent head arrives ready for installation in ordinary-hazard environments.

Browse our selection of upright and pendent Viking XT1 sprinklers.

Questions? Looking for XT1 products you don’t see here? Call us at +1 (888) 361-6662 or email support@qrfs.com.

This blog was originally posted at blog.qrfs.com. If this article helped you, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

4 thoughts on “#247 – XT1 Fire Sprinklers and Accessories: The “Next Generation” of Viking Sprinklers”

  1. Hello Sales Team,

    We require the following VIKING SPRINKLER SYSTEM and request you to send us your quote for the required items, details as given below:

    8 PCS.


    K-FACTOR: K-81







    MAKE: Viking, USA

    We hope you will find the above details sufficient to send us your quote. For any further information or clarification, please do not hesitate to contact us.

    Your earliest response shall be highly appreciated.



    Project Solutions (PROSOL)

    Unit #1101 – 29 Queens Quay East

    Toronto, ON M5E 0A4 Canada





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