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US 4,360,738 AGranted
Single probe low water control
AssigneeHoneywell Inc.
InventorJames I. Bartels
Life of this patent
Estimating the term…
Abstract
A timer means having a time delay on reapplication of control allows a single probe low water cutoff and feedwater makeup device to function. The time delay preventing reapplication of power to a burner while simultaneously causing a feedwater mechanism to add water to a boiler provides safe operation of the boiler without oscillations caused by momentary losses of water.
Claims9
A single probe low water cutoff and makeup water control, including:
- probe means having a first probe element adapted to normally be in contact with water in a boiler;
- said probe means further having a second probe element adapted to mount said probe means in a wall of said boiler;
- power supply means connected to said probe means to apply an electric potential between said elements;
- amplifier means connected to said probe means to detect the presence or absence of water between said probe elements by measuring the presence or absence of a current flow through the boiler water caused by said potential;
- said amplifier means including switching means having normally open circuit means and normally closed circuit means when water is absent from said boiler;
- said normally open circuit means adapted to control fuel burner means for said boiler and said normally closed circuit means adapted to control makeup water means for said boiler;
- and time delay means responsive to said amplifier means to initiate a time delay upon said normally closed circuit means closing after once having been opened by a change in water level at said probe means, and retaining its closed state for a fixed time delay period regardless of a subsequent change in water level at said probe means.
4 more elements
Dependencies are inferred from the claim text.