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Control Valves
Control valves are the final element of a control loop: they throttle flow continuously in response to a signal from the DCS or PLC. Seven Star LLC supplies control valves and their spare parts in Oman, with items led by Masoneilan and followed by Fisher, Flowserve and Samson. The category also includes Moog servo valves for hydraulic control and a sub-category of pressure independent control valves for chilled water (CHW) systems.
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Category guide
About Control Valves
Control valves are the final element of a control loop: they throttle flow continuously in response to a signal from the DCS or PLC. Seven Star LLC supplies control valves and their spare parts in Oman, with items led by Masoneilan and followed by Fisher, Flowserve and Samson.
The category also includes Moog servo valves for hydraulic control and a sub-category of pressure independent control valves for chilled water (CHW) systems.
Globe, rotary and severe service control valves
Sliding-stem globe valves are the general-purpose choice. The Masoneilan 21000 Series is a top-guided globe valve, the 41005 Series is cage-guided, and the 80000 Series three-way valves mix or divert flow. Rotary designs give more capacity for a given line size: the Masoneilan 35002 Camflex is an eccentric plug valve, the Fisher CV500 is a rotary globe valve, and the 39003 and 33000 Series are high performance and triple offset butterfly valves. For high pressure drops, multi-stage trims such as the 77000 labyrinth design reduce pressure in steps to limit cavitation, noise and erosion. A large share of the listing is seal kits, packing kits and trim parts for these series, so a worn valve can be overhauled instead of replaced.
HVAC control valves and servo valves
Pressure Independent Control Valves from Belimo, Danfoss, Frese and Siemens hold a set flow through fan coil and air handling units regardless of pressure changes elsewhere in the chilled water network. Moog pilot-operated servo valves belong to hydraulic motion control, where spool position follows an electrical command. pFlow flow control valves complete the list; Seven Star is the agency for pFlow in Oman and the GCC.
How a control valve is sized and specified
Sizing starts from the process data: fluid, flow rates at minimum, normal and maximum, inlet and outlet pressures, and temperature. From these the required flow coefficient (Cv) is calculated to IEC 60534, and a body size and trim are chosen so the valve works in the middle of its travel at normal flow. The inherent characteristic, usually equal percentage or linear, is matched to the process. Seat leakage class is defined by ANSI/FCI 70-2.
What to include in a control valve inquiry
Send the valve datasheet if one exists. Otherwise give size, pressure rating and end connections, process conditions or required Cv, trim type and characteristic, body and trim materials, shut-off class, actuator type with air supply and fail position, and the positioner signal. For spare parts the valve serial number is the most reliable reference.
What to include in your inquiry
These details let us quote the right item the first time.
- Valve type and size (DN / NPS)
- Pressure class and end connection
- Body and trim material
- Fluid, flow rate, inlet and outlet pressure, temperature
- Actuator type and fail position
- Accessories: positioner, limit switches, solenoid
Missing some of them? Send what you have. A nameplate photo or an old part number is enough to start.
Top brands in Control Valves
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Guides and articles
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Control Valve Selection and Sizing: Cv, Characteristics, Cavitation, Noise and Choosing the Right Valve Style
Best 5 Fittings and Valves Suppliers in Middle East: Your Ultimate Procurement Guide for Oman’s Industrial Success
Electric Valve Actuator Selection Guide: Multi-Turn, Part-Turn and Linear Actuators for Oil, Gas and Water Service
Request a Quote for Control Valves
Looking for a specific model, part number or brand in Control Valves? Send us your requirements and quantities. Seven Star LLC sources genuine industrial equipment for customers across Oman and the GCC and replies with a formal quotation.
- Genuine OEM products
- Supply across Oman & the GCC
- Formal quotation from our sales team
Free, no-obligation quotation · takes about 1 minute
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Frequently Asked Questions
When should I choose a rotary control valve instead of a globe control valve?
Globe valves offer the widest choice of trims, handle high pressure drops well and are easy to maintain in line. Rotary valves such as eccentric plug, segmented ball and butterfly types pass more flow for the same line size, weigh less and have a rotary stem seal that is less prone to leak. Globe is typical for small sizes and severe drops, rotary for larger lines and moderate drops.
What is the difference between an equal percentage and a linear trim?
With a linear trim, flow capacity changes in direct proportion to travel. With an equal percentage trim, each increment of travel changes capacity by a constant percentage of the current value, so the valve is fine at low openings and coarse at high ones. Equal percentage suits loops where the pressure drop across the valve falls as flow rises, which is the more common case.
How do I order the correct seal kit or packing kit for a control valve?
Quote the serial number from the valve nameplate. The manufacturer's build record for that number shows the body size, trim size, packing material and any special options, and the kit is selected from it. If the plate is missing, send the series, size, pressure rating, trim type, stem diameter and packing material, with a photo of the valve.
What is the difference between cavitation and flashing in a control valve?
Both begin when liquid pressure inside the valve falls below vapor pressure and bubbles form. In cavitation the pressure recovers downstream and the bubbles collapse, causing noise and pitting damage. In flashing the outlet pressure stays below vapor pressure, so the fluid leaves as a liquid and vapor mixture. Cavitation is controlled with multi-stage trims; flashing is handled with hardened materials and body design.
How does a pressure independent control valve differ from a standard two-way valve in a chilled water system?
A standard two-way valve passes more or less water as system pressure changes, so circuits interact and need separate balancing valves. A pressure independent control valve has a built-in differential pressure regulator that keeps the pressure across the control element constant. Flow then depends only on actuator position, and the maximum flow is set on the valve itself.
Do you supply control valves in Oman and the other GCC countries?
Yes. Seven Star LLC is based in Muscat and quotes control valves for buyers in Oman, the UAE, Saudi Arabia, Qatar, Kuwait and Bahrain. Buyers in other countries can also send a request. For a quotation, send the valve serial number or the process data sheet (fluid, flow, pressures, temperature, line size) through the inquiry form.
Which control valve brands can Seven Star quote?
This category currently lists items from Masoneilan, Fisher, MOOG, Flowserve, Danfoss, Samson, Belimo and Neles. Other manufacturers can be quoted on request: send the brand and the model or part number, and we will confirm whether we can source it.