Pilot Operated
Safety Valves
Series 810 – Pop Action
Series 820 – Modulate Action
A new range of High Efficiency pilot operated safety
valves from Leser – and on Short Lead Times
Series 810 and 820 Overview
LESER Pilot Operated Safety Valve (POSV)
LESER Pilot Operated Safety Valves (POSVs) are designed
according to the API 526 standard. The full
range of sizes from 1" x 2" up to 8"
x 10" (DN 25 –DN 200) with all orifices
from D – T are available for
pressure ratings up to pressure class 600 x 150.
Beyond API 526, LESER offers so-called Extra Orifices
(also known als Full Port or Full Bore nozzles).
The Extra Orifices provide maximum capacity in relation
to valve size. In addition, LESER POSVs come in two
different functional designs, i.e. Pop Action (Series
810) and Modulate Action (Series 820). These designs
determine the POSVs operating characteristics. Depending
on their design, LESER POSVs open rapidly (Series
810 – Pop Action) or gradually in proportion
to system pressure (Series 820 – Modulate Action).
Series 810 – Pop Action
LESER POSVs Series 810 with rapid opening
(Pop Action)
• are used for applications where the certified
discharge capacity needs to be reached quickly
• are used for gas applications only
• have an adjustable blowdown of 2 – 7%
of set pressure conforming to ASME VIII which can
be adjusted beyond API standard up to -15%
Series 820 – Modulate
Action
LESER POSVs Series 820 with proportional opening (Modulate
Action)
• are used to minimize medium loss
• are used if medium must not discharge to atmosphere
• open in proportion to the overpressure to
ensure that only as much mass flow is discharged from
the
safety valve as is necessary to prevent further pressure
increase
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