US3834357A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low-water cut off system
Assignee: TDK Micronas GmbH
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Filing: 1973-06-07
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Granted: 1974-09-10
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Expires: 1993-06-07
Abstract
Abstract A system is disclosed for monitoring the water level in hot water boilers or the like and, when the water level falls below a prescribed level, turning off a burner and sounding an alarm. The system includes a manual control for testing whether the system is actually functioning, or not, and also whether it is functioning efficiently, or not. It incorporates improved probe means and means enabling servicing to be more efficiently carried out. Manual reset, or start, means are included to assure that the system will start-up after halting only when an attendent is at hand and thus prevents dry-firing.
Inventors
- 👤 L Kaczmarek
- 👤 C Adamson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:28
CPC Classifications
F; F22; F22B; F22B37/00; F22B37/02; F22B37/42; F22B37/44; F22B37/443
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
215 words
A low water sensing and cut-off system comprising an electric circuit, means in said circuit for receiving electric power, a probe assembly including a probe element forming one terminal of the electric circuit, said probe element enabling the electric circuit to be completed through water in contact with the probe element to a second terminal of the electric circuit, said probe element causing a pre-existing electric circuit to be broken when water drops out of contact with the probe element, manually controlled switching means for establishing an electric circuit through the probe element and water in contact with the probe element, relay means forming part of said electric circuit, said relay means including a normally open and a normally closed contact, said manually controlled switching means including a normally open momentary-contact switch responsive to manual pressure to complete said electric circuit and to energize said relay when the electric circuit through the probe assembly is completed, said relay operating to close a normally open contact to enable a latching circuit around said normAlly open momentary-contact switch to maintain an electric circuit so long as water remains in contact with elements of said probe assembly, and said relay releasing to reset its contacts in response to loss of contact between said probe assembly and the water.
Claim 2
Dependent Claim
215 words
A low water sensing and cut-off system comprising an electric circuit, means in said circuit for receiving electric power, a probe assembly including a probe element forming one terminal of the electric circuit, said probe element enabling the electric circuit to be completed through water in contact with the probe element to a second terminal of the electric circuit, said probe element causing a pre-existing electric circuit to be broken when water drops out of contact with the probe element, manually controlled switching means for establishing an electric circuit through the probe element and water in contact with the probe element, relay means forming part of said electric circuit, said relay means including a normally open and a normally closed contact, said manually controlled switching means including a normally open momentary-contact switch responsive to manual pressure to complete said electric circuit and to energize said relay when the electric circuit through the probe assembly is completed, said relay operating to close a normally open contact to enable a latching circuit around said normAlly open momentary-contact switch to maintain an electric circuit so long as water remains in contact with elements of said probe assembly, and said relay releasing to reset its contacts in response to loss of contact between said probe assembly and the water.
Claim 3
Dependent Claim
105 words
A system as claimed in claim 1, in which the switching means includes a normally closed test switch forming part of a test circuit, said test circuit includes lamp means shorted across the terminals of the test switch when the switch is at rest. said lamp means being energized when said test switch is operated, power is on, and a probe element of the probe assembly is in contact with water in a tank, and said lamp means being de-energized when the test switch is operated and either the power is off or the element of the probe is out of contact with the water.
Claim 4
Dependent Claim
19 words
A system as claimed in claim 2, in which the test switch consists of a momentary-contact, normally closed switch.
Claim 5
Dependent Claim
43 words
A system as claimed in claim 2, in which the lamp is selected to be visibly responsive to variations in the level of current flow, glowing brighter when the probe assembly is clean and dimmer when the probe is contaminated with mineral deposits.
Claim 6
Dependent Claim
51 words
A system as claimed in claim 1, in which the probe assembly incorporates a probe element for establishing electrical contact with water in a tank, the probe element is U-shaped to enable a self-cleaning function, and the probe element is secured to the probe assembly at the base of the U.
Claim 7
Dependent Claim
71 words
A system as claimed in claim 1, in which the probe assembly incorporates a probe element for establishing electrical contact with water in a tank, the probe element is formed from a flat strip of stainless steel, and the strip of steel is bent at 90* angles, forming a U-shaped probe element having sharp corners to maximize the cleaning effects of heating and cooling on mineral deposits on the probe element.
Claim 8
Dependent Claim
76 words
A system as claimed in claim 1, in which the probe assembly incorporates a probe element for establishing electrical contact with water in a tank, the probe element is formed from a flat strip of stainless steel, and the strip of steel is bent in the form of a candy ribbon when viewed along a narrow edge, said bend maximizing the cleaning effects of heating and cooling on mineral deposits which accumulate on the probe element.
Claim 9
Dependent Claim
54 words
The invention as claimed in claim 1, in which release of said relay causes said latching circuit to release, thereby returning said system to a neutral state with power terminals connected to an alarm system and the burners turned off, release of said relay thus preventing any possibility of boiler damage due to overheating.
Claim 10
Dependent Claim
60 words
The invention as claimed in claim 1, including a housing, and connector means connecting said probe assembly to said housing, said connector means including adjustable elements to hold said housing and said probe assembly together, and means by which said adjustable elements may be loosened enabling separation of said housing and said probe assembly without removal of said adjustable elements.
Claim 11
Dependent Claim
49 words
The invention as claimed in claim 1, including a housing connected to said probe assembly via connector means to complete the low water sensing and cut-off system, said probe assembly incorporating means enabling the direct connection of the low water sensing and cut-off system to a hot water tank.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-09 | 1978-03-11 | 1978-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-09 | 1982-03-11 | 1982-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-09 | 1986-03-11 | 1986-09-10 | $7700.00 | Window Closed / Lapsed |