الدعم والخدمات

سؤال وإجابة عن المنتج

Safety and Relief Valve


QWe would like to have AL-52FS-95 in a different set pressure.

Please contact us.

QDo you have AL-52F with set pressure 97kPa JIS approved?

It is not available with JIS approval.

QIs it OK to fix the lever of AL-52F?

Please do not fix the lever. We recommend operating the lever (draining water) 1 or 2 times per month, but this is not possible if the lever is fixed. Besides, it will be very dangerous as it will prevent the relief valve from operating properly to protect the system.

QCan we use resin hose on the outlet side of the safety valves?

Please use metal pipes.

QDo you have safety valves with less seat leakage?

We recommend AL-150T and AL-140T with excellent tightness.

QAre there safety valves with superior corrosion resistance?

We recommend the AL-150 Series safety relief valve, in which SCS14A is used for the valve and valve seat.

QMaterial of the safety relief valve we use now has valve and valve seat made of SUS304, but we are worried about corrosion. Are there any products superior in corrosion resistance?

For the AL-150 Series safety relief valve standard product, SCS14A (equivalent to SUS316) with superior corrosion resistance is used for the valve and valve seat.

QAre there safety relief valves with good valve seat tightness suitable for liquid?

The safety relief valve equipped with an O-ring is available, using a soft seat for the trim parts to provide the valve seat with excellent tightness. (Model: AL-150T/-150TR/-150TML/-140T)
For oil use, please contact us for further information.

QIs there any standard in selecting a safety valve for warning installed at the outlet side of a pressure reducing valve?

Regarding discharge capacity, selection practice differs among regions, industries and applications etc. The safest way is to select a safety valve covering the maximum flow rate of the pressure reducing valve.
As for the set pressure, please refer to the following table.

QWhat is the difference between a lift type and a full bore type?

For the lift type safety valve, a lift of valve seat is more than 1/40 or under 1/4 of an inside diameter of a valve seat opening, and a flow passage area (a curtain area) of valve port becomes the smallest in flow passage area when a valve disc opens.
For the full bore type safety valve, the flow passage area at valve seat is bigger enough than the nozzle throat area at the inlet side.
In Yoshitake's lineup, lift type models are named AL-XX series and full bore type models are named AF-XX series.

QPlease explain about the back pressure at the outlet side of a safety valve.

There are two kinds of "back pressure" of a safety valve.
1. Accumulated back pressure (Pressure at the outlet side of the valve, which is generated by the flow at the outlet side when the valve starts to blow.)
2. Existing back pressure (Pressure which already exists before the valve starts to flow. The pressure is generated by the other sources of supply).

When the back pressure generated as the valve starts to blow exceeds the permissible value (approximately 10% of the blow out pressure), the activation in closing is badly influenced. JIS B 8210 requires deciding the back pressure of blowing pipe according to a safety valve subject to a limit of the lowest back pressure.

QWhat are the differences among safety valves, safety relief valves and relief valves?

A safety valve is mainly used to ensure safety of a vapor (steam or gas) generator, which operates instantly and automatically when the vapor pressure exceeds the specified value (Referring to JIS B 8210). A relief valve is mainly used to relieve excess liquid (water / oil) pressure. It is automatically opens depending on the pressure increase, in case the liquid pressure reaches the set pressure.
A safety relief valve is mainly installed on pipings, and it can be used for both gas and liquid.

QCan Yoshitake safety valves be used for antifreeze solution/brine, such as ethylene glycol?

No, because adhering material or stuck deposit can cause malfuction.

QWhat is allowable leakage rate of the valve seat?

It depends on model.

QCan we re-adjust safety valves and relief valves at site?

Please specify the set pressure at the time of order, or re-adjustment at factory is required. Please contact us or our local distributor in your country/area.

QShould we install a strainer on the inlet side of a safety relief valve?

Do not install a strainer on the inlet side.

QCan safety valves be disassembled and repaired at site?

No, they have to be serviced at factory.

QWhen a safety valve operates, will the fluid come out from the part other than the valve's outlet?

It depends on the valve's structure.
1) Closed type: only from the outlet
2) Open type: the fluid can come out from open part of the spring case, cap and lever part (sliding part of the spindle) and back pressure pipe.

QCan we plug the outlet of the back pressure adjusting valve?

The part cannot be plugged because it adjusts the blowdown by adjusting back pressure above the valve disc.

QCan safety valves be used with the back pressure on the outlet side?

No, they cannot.

QThe safety valve does not stop discharge.

Safety valves stop blowing only if the inlet pressure drops to the re-seating pressure.

QHow detailed can safety valves be set?

Set pressure up to 0.129MPa: by every 0.002MPa
Set pressure 0.13-0.26MPa: by every 0.005MPa
Set pressure higher than 0.26MPa: up to the second after decimal point (in MPa)

QWhat is the plug on the safety valve body for?

To drain condensate (water) inside the safety valve body.

QShould we select lift type or full bore type safety valve for pressure vessels?

Both types can be selected as long as the valve satisfies the required discharge capacity.

QCan safety valves be used beyond its maximum working pressure?

Please use it within its working pressure.

QHow should we construct the outlet side of a safety valve (for steam or air) ?

Please refer to "Guidelines for Installing Safety Valve."

QWhat is "accumulation" of a relief valve?

Rate of allowable overpressure is called accumulation.

QIs a calculation sheet for safety valve's discharge capacity available?

Yes, please contact us.

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