кто-нибудь знает, что за эффект такой?

контекст:
With Trevitest Hot Testing you get a date
marked certified print out of valve set
pressure and the line pressure at the valve.
From this information the set pressure,
spring adjustment and displacement of the
valve can be determined. Trevitest also
gives an indication of the effect of the
nozzle ring, guide ring and reseat pressure.