from The Century Dictionary.
- noun A valve capable of very fine adjustment.
- noun A valve having a stem with a sharp conical point which bears on a conical seat. The stem is made to travel by a very fine screw, and a large turn of the handle is required to make a small change in the opening through the valve.
- noun A similar valve controlling an opening of very small size.
Sorry, no etymologies found.
In order to maintain a constant load, a needle-valve has been provided, which, when the pump is operated at its lowest speed, will allow a sufficient quantity of oil to flow into the main cylinder to equalize whatever leakage there may be.
If the water-supply is mainly controlled by a needle-valve, it is useful to connect the burner with the carbide vessel through a short length of rubber tube; and if this plan is adopted, a cock can, if desired, be put close to the burner.
If it is contaminated with undissolved matter, the dirt will eventually block the fine orifices, especially the needle-valve, or will choke the pores of the wick or the felt pad.
In such apparatus the supply of water is usually controlled ultimately by pressure, though a hand-operated needle-valve is frequently put on the water tube.
The water enters at A, and the flow is regulated by the needle-valve at left-hand side.
At this point, the supply of oxygen is cut off, the valve connecting the tension-equalizer with the main system is opened, and simultaneously the needle-valve on the reduction-valve of the oxygen cylinder is tightly closed, preliminary to weighing the cylinder.