The TYCO TY3935 is the dry pendent model of the DS-1 QR series, with a K 5.6 discharge coefficient and 3/4″ NPT thread, quick response and standard coverage, operated by a glass bulb 3 mm. It is designed for places where the sprinkler or part of the piping is exposed to freezing, such as drops into freezers, unheated attics and piping extensions through a wall to loading docks and overhangs. A dry-type sprinkler installed pendent, with its barrel extending into the area exposed to freezing. For where the sprinkler sits in the whole system, see the complete guide to sprinkler systems in Saudi Arabia.
In short
- Model (SIN): TY3935 — Dry Pendent.
- Discharge coefficient K 5.6, 3/4″ NPT connection.
- Glass bulb 3 mm, quick response.
- Temperature ratings in the datasheet: 57 / 68 / 79 / 93 / 141 °C.
- Maximum working pressure: 175 psi (12.1 bar).
- Series approvals: UL, C-UL, FM, NYC, EAC (per Tables A and B). The approval of each model, finish and rating is in the approvals table of datasheet TFP510.
How this sprinkler works
The glass bulb contains a fluid that expands when exposed to heat. When the rated temperature is reached, the fluid expands enough to shatter the bulb, the sprinkler opens and the deflector spreads the water over the fire area.
In a dry-type sprinkler a plug with sealing assembly at the inlet keeps water out of the sprinkler barrel while in service. When the element operates, the seat is released and a spring drives the plug clear, so water enters and discharges. The barrel extending into the cold area therefore stays free of water.
A dry-type sprinkler installed pendent, with its barrel extending into the area exposed to freezing. Quick response means the thermal element reacts faster, so the sprinkler operates earlier than a standard-response sprinkler of the same rating.
Models in the series
| SIN | Orientation | K-factor | Thread |
|---|---|---|---|
| TY3135 | Dry Upright | 5.6 | 1″ NPT |
| TY3235 | Dry Pendent | 5.6 | 1″ NPT |
| TY3335 | Dry Horizontal Sidewall | 5.6 | 1″ NPT |
| TY3735 | Dry Horizontal Sidewall | 5.6 | 3/4″ NPT |
| TY3935 — this model | Dry Pendent | 5.6 | 3/4″ NPT |
Links to the other models are in the “Similar models” table below. The choice of model comes from the hydraulic calculation, hazard classification and installation method in the project design.
Application notes
- Quick response with a 3 mm bulb. Finishes: natural brass, chrome or signal white. Some listings are for light and ordinary hazard only per the table.
Technical data
| Item | Value |
|---|---|
| Model (SIN) | TY3935 |
| Orientation | Dry Pendent |
| Discharge coefficient | K 5.6 gpm/psi½ (80.6 L/min/bar½) |
| Thread | 3/4″ NPT |
| Element and response | Glass bulb 3 mm — Quick Response |
| Coverage | Standard Coverage |
| Temperature ratings | 57 / 68 / 79 / 93 / 141 °C |
| Maximum working pressure | 175 psi (12.1 bar) |
| Installation torque | 10 – 20 lb-ft (13.4 – 26.8 N·m) |
| Wrench | W-Type 7 |
| Escutcheon | Style 10 or the escutcheons specified in the datasheet |
| Approvals | UL, C-UL, FM, NYC, EAC (per Tables A and B) |
| Datasheet | TYCO TFP510 |
The critical point: fitting and exposed length
A dry-type sprinkler must be installed only in the fittings listed in the datasheet’s Design Criteria. On wet systems the exposed barrel length in the warm area must meet the minimum in the table for the protected-area temperature.
Installation steps
- Inspect before installing: never install a sprinkler whose bulb is cracked or has lost liquid.
- Confirm the fitting is one of the types listed in the datasheet’s Design Criteria section.
- Install the sprinkler in its correct orientation (Dry Pendent) as shown in the datasheet — never reversed.
- Apply pipe-thread sealant to the threads, then hand-tighten the sprinkler.
- Finish with the specified wrench (W-Type 7) within 10 – 20 lb-ft (13.4 – 26.8 N·m). Higher torque can distort the inlet and cause leakage.
- With an escutcheon, use only the specified one (Style 10 or the escutcheons specified in the datasheet) and never compensate for adjustment by changing the torque.
Common mistakes
- Installing the dry sprinkler in an unlisted fitting, or with less than the minimum exposed length in the table, so water freezes inside the barrel.
- Installing a sprinkler that was dropped, struck or slipped by the wrench. The datasheet requires any such sprinkler to be replaced.
- Painting or coating sprinklers on site. Sprinklers must not be altered after leaving the factory; altered sprinklers are replaced.
- Hanging objects from sprinklers, or cleaning them with anything other than a gentle feather duster.
Maintenance
Sprinklers that leak or show visible corrosion must be replaced, as must sprinklers exposed to corrosive products of combustion that cannot be fully cleaned. The owner is responsible for inspection, testing and maintenance to NFPA 25 and the authority having jurisdiction, preferably by a qualified inspection service. Before closing a main control valve for maintenance, obtain permission from the proper authorities and notify everyone affected.
Files and ordering
TYCO datasheet TFP510 and the available approval certificates are in the files section of this page. When ordering, state the model TY3935, temperature rating and finish, escutcheon, and the required length. The datasheet lists the part numbers (P/N) for each combination.
How to order
Use the “Build your order” section on this page: add every model and quantity, then send the whole order by email or WhatsApp. It reaches us as a tidy PDF request sheet and we contact you with the quotation.
FAQ
What does TY3935 mean?
It is TYCO’s Sprinkler Identification Number (SIN). It identifies the exact model — orientation, K-factor and thread. The sprinkler is ordered by this number together with temperature rating and finish.
How do I choose the temperature rating?
From the highest expected ceiling temperature and the rating classes in the project’s governing standard, within the ratings available for this model in the datasheet.
Do all models in the series carry the same approvals?
Not always. The approvals table in datasheet TFP510 gives each model’s approvals by rating and finish, so check it when the project requires a specific approval.
What is the benefit of quick response?
The thermal element reacts faster, so the sprinkler operates earlier and limits heat and smoke spread; standards require it in some occupancies such as light hazard.
Why a dry-type sprinkler rather than a standard one?
The barrel extending into the cold area stays free of water until operation, so it cannot freeze, while the water stays in the heated part of the system.
References
- TYCO TFP510 — Series datasheet (attached)
- NFPA 13 — Standard for the Installation of Sprinkler Systems
- NFPA 25 — Inspection, Testing and Maintenance of Water-Based Fire Protection Systems
- TYCO TFP700 — Installer warning for handling and installing sprinklers
This page is general information to help with selection and ordering, taken from the attached TYCO datasheet. Final design is set by the project’s approved designer; the project specification, the consultant’s drawings and the latest datasheet revision govern.
