The floating ball valves and trunnion ball valves are both quarter-turn valves that provide a bubble-tight seal for bi-directional sealing under both low and high-pressure conditions. Nevertheless, each type possesses its own distinct advantages and disadvantages, particularly when comparing floating and trunnion-mounted ball valves.
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Comparing Floating Ball Valve and Trunnion Ball Valve
| Floating Ball Valve |
Trunnion Ball Valve |
| Construction |
The ball will shift towards the seat when flow pressure is applied, while the seat stays stationary. |
| Working Principle |
The flow pressure drives the seat towards the ball for sealing. |
| Function |
On/off control, self-relieving seat |
| Open Speed |
Quarter turn for quick operation |
| Suitable Fluid |
Oil, gas, petrochemical, wastewater, etc., hydraulic power |
| Suitable Pressure & Size |
Class 150-300, 1/2"-6";
Class 600, 1/2"-3";
Class 900, 1/2"-2";
Class , 1/2"-1" |
| Flow Direction |
Bi-directional, single direction |
| Torque |
Higher |
| Seat Material |
Soft, metal seat |
| Suitable Temperature |
-196 to 625°C |
| Design Standard |
API 6D, API 608, BS |
| Price |
Lower |
Floating Ball Valve Overview
A floating ball valve derives its name from the design of the ball, which "floats" freely within the valve's body, compressed between two flexible seats while suspended in liquid. During operation, the ball typically floats slightly downstream, causing the seating mechanism to compress under it. If the seat fails, the ball will float against the metal stem to create a seal, offering a protective mechanism within its design.
Floating ball valves are prevalent in the piping industry, effectively regulating flow across pipelines in the gas, oil, and water sectors. They establish a bi-directional seal and can be customized for high-pressure applications, though they are typically suited to low to medium-pressure pipelines. Floating ball valves can come in various configurations and sizes and feature a hollow perforated ball for fluid passage when open.
As the nominal bore size of the ball increases, so does its weight, thereby increasing the area subjected to line pressure. Eventually, the seats may no longer support the ball, necessitating a different design, which is where the trunnion-mounted ball valve becomes relevant.
Advantages of Floating Ball Valves:
- Cost-effectiveness
- Easier maintenance due to fewer components
- Reduced manufacturing time
Disadvantages of Floating Ball Valves:
- Dependence on downstream seat under moderate loads
- Increased torque at the same size and operating conditions
- Seating absorbs the gravity of the ball, limiting its ability to handle higher pressures or larger sizes
Trunnion Mounted Ball Valve Overview
There comes a point where higher loading forces on the ball exceed what the seats can support, thus requiring an alternative design. A trunnion mounted ball valve features a ball constrained by bearings, allowing only rotation while bearing most of the hydraulic load, leading to lower bearing pressure and no shaft fatigue. In this design, the shaft, ball, and trunnion act as a collective assembly that supports the ball, while the seats "float" in contrast to the floating ball arrangement, thus enabling bi-directional sealing.
Advantages of Trunnion Mounted Ball Valves:
- Lower torque; advantageous for actuation and reducing actuator size, thereby cutting overall costs.
- Capable of consistently withstanding higher pressures and larger balls.
Disadvantages of Trunnion Mounted Ball Valves:
- Higher initial cost
- Not ideal for very small sizes, typically below 1-1/2"
Related Products:
8 inch ball valve, 26 inch ball valve, 28 inch ball valve, 30 inch ball valve
For more information, please visit YIYUAN.
If you're interested in more details, kindly visit Customized Trunnion Mounted Ball Valve.
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