Control of a large bore scotch yoke actuator on a refinery.
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The customer was suffering from unplanned downtime caused by the failure of a solenoid valve installed on a scotch yoke actuator, which was controlling a large and critical on/off valve.
The solenoid valve failures were caused by a build-up of dirt on the valve internals. The dirt was able to enter the valve due to the construction of the valve which relied on a breather hole that was open to the atmosphere.
The customer was looking for a replacement solenoid valve that was proven in use in similar applications, that did not have a breather hole that was open to the atmosphere, and that was able to pass a high flow rate, in order to meet the opening and closing speed requirements of the large actuator and valve assembly.
ASCO provided an Ex d rated direct acting 327 series solenoid valve. The 327 series is ideal for use in applications such as this, because:
It has a “non-breathing design” which means the internals are not affected by any dirt or corrosive elements in the external atmosphere.
In applications where the pneumatic air may have entrained particles, the special PTFE
guiding ring reduces the risk of internal friction and sticking.
Instead of the O-rings used by many manufacturers, the 327 series uses
double delta seals which do not deteriorate over time. As O-rings deteriorate they can cause increased friction which may, in time prevent the valve from functioning.
Because, thanks to the use of the Double Delta Seal concept, the friction does not increase over time there is no need for a heavy spring. This means that
lower power coils can be used, which in themselves can offer advantages in terms of operating lifetime.
The KV of 1.5 means that relatively high flow rates can be achieved without the use of pneumatic volume boosters.
The valves are proven in use and have an
exceptional service life, which is emphasised by the valve’s SIL3 capability (Exida and TÜV approvals).
The ASCO 327 is available in NACE compliant materials. This applies to the internal components (not just wetted parts) and the external components. This means that even when the solenoid housing is open to the atmosphere all components are resistant to Stress Corrosion Cracking.
The likelihood of the solenoid valves causing a spurious trip have been greatly reduced, resulting in improved uptime.
In the exceptional case that maintenance of the valve may be required, the 327 series coil is field replaceable, meaning the solenoid valve can stay in line and the pneumatic connections need not be broken.
An additional benefit was the valve’s reduced power consumption by almost 50%: from 15W to 8W. This was possible thanks to the low spring force of the 327 series solenoid valve. This could save the customer costs on future installations as thinner cables are required and there is no need for intermediate relays.
To select a 327 series, or request a quote, please go to the
327 series page
For more information on the benefits of the 327 series solenoid valve, visit the
To see the 327 video where the design of the valve is explained, please click
For all our certificates and approvals, including SIL, please go to
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