For on-line pressure safety valves testing, motor drive have several advantages verso hydraulic drives. Here are some explanations on your questions raised:
The safety valve is not closed after the test. We don’t have enough difference between system working pressure and safety valve opening point! How to overcome this unpleasant situation?
Yes, this is large benefit of Legatest drive fast response. How?
Legatest technology and fast response allows fast determination of safety valve opening pressure while the expansion of steam power does not constitute such a force on the valve plug parts that would lead to full stroke. In this point the valve plug fast turn back to the valve seat.
In this case there is much less possibility of contamination of the valve and consequently leaks after the test.
Also the system pressure and medium losses are smaller.
However, acoustic sensor technology allowed the determination of leakage differences before and after the on-line test.
Opening pressure is sometimes hard to determine when the hidraulic drive is used. Why?
Motor drive has superior dynamic properties which reflect the following characteristic:
- Better control of pulling force.
- No negative hydraulic influences which may prevent proper and accurate determination of safety valve opening pressure and other functional characteristics.
How motor drive influences on safety of work?
Because of motor consumption monitoring and factory calibration with force, some advantages have been made:
- System overload protection – the maximum motor pulling force is mechanically limited so that the respective deign values of the components are not exceeded
- Power monitoring – an electronic system monitors if the supplied current and tension meet the requirements of the test conditions
- Power calibrating function – protect the system in the case of force sensor failure indication with factory calibration (comparison) of motor electric consumption with force chain values.
The valves are sometimes installed in very inaccessible areas. Management of the test should be done so by vast distances.
Legatest motor drive technology enables management and monitoring the test on a long distance (standard 50 m, 10mm or longer is possible). Communication connection between PC and Legatest drive with cables diameter 4 mm is quickly and easily unlike thick hydraulic hoses.
Communication speed is 30 ms in opposite of hydraulic slower response and hysteresis.
Slow communication reduces on-line testing safety!
The on-line testing with Legatest could be extremely effective due implemented technology and design parts.
28 safety valves on line testing in one day – Legatest client record from Germany.
Using the hydraulic device, these safety, accuracy and useful features cannot be implemented.
How is the power supply? In some environments it is difficult to access or prohibited because of potentially explosive areas…
Legatest device is power autonomous. Near motor drive accumulator batteries are mounted. With full charged batteries 200 normal on-line safety valves tests can be implemented (50 tests up to 50 kN).
Legatest device can be use in potentially explosive atmospheres according to directive 94/9/EC, approvals include:
- EC Type Examination Certificate Nr: SIQ 11 ATEX 134 X for Ex cones: II 2 G Ex d(ib) ib IIC T4 Gb
- Under manufacturing, each device separately is approved: Certificate of Conformity Nr: LT III Eex….