Description
Watson McDaniel O-Series — Pressure Regulating Valve for Steam (Phosphor Bronze Diaphragm)
The O-Series Pressure Regulating Valve provides an economical and reliable solution for reducing pressure in steam systems. Constructed with a cast iron body and hardened stainless-steel internals, the O-Series is designed for long service life and stable performance. It is the most popular Watson McDaniel direct-operated regulator for steam applications.
Product Overview
- Direct-operated regulator for pressure reduction in steam systems
- Equipped with Phosphor Bronze diaphragm (Code B) — for steam applications only
- Compact design for easy installation and maintenance
- Ideal for process, heating, and distribution steam systems
Technical Specifications
- Body Material: Cast Iron
- Seat: Stainless Steel (Teflon® optional)
- Diaphragm: Phosphor Bronze
- Maximum Inlet Pressure: 250 PSIG
- Minimum Inlet Pressure: 15 PSIG
- Maximum Pressure Reduction: 125 PSI
- Maximum Differential Pressure: 15 PSI
- Connection: Threaded NPT (3/8″ to 2″ sizes)
Available Models — Single Spring (Phosphor Bronze Diaphragm for Steam)
| Size / Connection | Model Code | Reduced Pressure Range (PSIG) | Weight (lb) |
|---|---|---|---|
| 3/8″ NPT | O-11-N-13-B / O-11-N-14-B / O-11-N-09-B / O-11-N-10-B | 0–10 / 10–50 / 40–100 / 100–200 | 10 |
| 1/2″ NPT | O-12-N-13-B / O-12-N-14-B / O-12-N-09-B / O-12-N-10-B | 0–10 / 10–50 / 40–100 / 100–200 | 10 |
| 3/4″ NPT | O-13-N-13-B / O-13-N-14-B / O-13-N-09-B / O-13-N-10-B | 0–10 / 10–50 / 40–100 / 100–200 | 10 |
| 3/4″ HC | OHC-13-N-0003-B / OHC-13-N-0004-B / OHC-13-N-0005-B / OHC-13-N-0006-B | 0–10 / 10–50 / 30–50 / 40–85 | 15 |
| 1″ NPT | O-14-N-0008-B / O-14-N-0009-B / O-14-N-0010-B / O-15-N-0008-B | 10–30 / 30–50 / 40–85 / 0–10 | 19 |
| 1¼″ NPT | O-15-N-0009-B / O-15-N-0010-B | 30–50 / 40–85 | 19 |
| 1½″ NPT | O-16-N-0008-B / O-16-N-0010-B / O-16-N-0011-B | 10–30 / 40–85 / 30–50 | 47 |
| 2″ NPT | O-17-N-0008-B / O-17-N-0009-B / O-17-N-0010-B / O-17-N-0011-B | 10–30 / 30–50 / 40–85 / 30–50 | 48 |
Available Models — Double Spring (Phosphor Bronze Diaphragm for Steam)
| Size / Connection | Model Code | Reduced Pressure Range (PSIG) | Weight (lb) |
|---|---|---|---|
| 3/4″ HC | OHC-13-N-0708-B / OHC-13-N-0809-B | 0–75 / 30–130 | 19 |
| 1″ NPT | O-14-N-0809-B / O-14-N-0910-B | 0–75 / 30–130 | 22 |
| 1¼″ NPT | O-15-N-0910-B | 30–130 | 22 |
| 1½″ NPT | O-16-N-0809-B / O-16-N-0910-B | 0–75 / 30–130 | 48 |
| 2″ NPT | O-17-N-0809-B / O-17-N-0910-B | 0–75 / 30–130 | 48 |
Options & Adders
- Teflon Soft Seat for Tight Shut-Off (Suffix Code 6T): Add 5%
- High-Capacity (HC) Models: Available for 3/4″ size
Important Application Note
- Use Phosphor Bronze diaphragms for steam service only.
- Use Viton diaphragms for air, water, or oil applications.
- Do not use phosphor bronze diaphragms on liquids — they may fracture.
Note: The O-Series Regulators are direct-operated valves for steam pressure reduction and are not standalone shut-off devices.