GB1582891A

GB1582891A - Humidifier

Info

Publication number: GB1582891A
Application number: GB469776A
Authority: GB
Original assignee: HUMIDIFIER GROUP Ltd
Current assignee: HUMIDIFIER GROUP Ltd
Priority date: 1977-05-05
Filing date: 1977-05-05
Publication date: 1981-01-14

Description

(54) IMPROVED HUMIDIFIER (71) We, HUMIDIFIER GROUP LI MITED, a British Company of 21 Napier Road, Bromley BR2 9JA Kent, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following Statement: This invention relates to an evaporation humidifier of the silent steam type and comprising an "open-topped" reservoir for water, an electrical heater for raising the temperature of water in the reservoir and temperature control means to prevent water in the reservoir from boiling. The term "open-topped" as used above does not exclude the location of a grille over the top of the reservoir.

Evaporation humidifiers of the kind described with a cylindrical reservoir have heretofore employed, for the electrical heater, a narrow heating element which encircles the cylindrical wall near the base of the reservoir, thermal conduction through the ring of cylindrical wall of the reservoir being relied on to heat the water contained therein.

We have now found that considerably enhanced efficiency of operation of an evaporation humidifier of the kind described can be obtained by a repositioning of the electrical heater. According to the present invention an evaporation humidifier comprises a housing, an opening in the housing through which water vapour can leave the housing, an open-topped reservoir for water within the housing, an electrical heater for raising the temperature of water in the reservoir and temperature control means to prevent water in the reservoir from boiling, the heater being in the form of a hot plate which underlies a watersupporting surface of the reservoir which surface is horizontal when the housing is in its normal position for use.

Coveniently the opening in the housing is formed in the top thereof and is defined by a grille. The reservoir is preferably made of a synthetic plastics material and suitably one enjoying fungicidal properties.

Among the alternative arrangements for the electrical heater may be mentioned: a) utilising an electrically-heated hotplate which is in intimate thermal contact with the underside of the bottom of the reservoir and is permanently attached thereto, and b) utilising an electrically-heated hotplate and removably locating the reservoir over the hotplate.

Prior art open silent steam type evaporation humidifiers have had the supply lead to the electrical heater permanently connected thereto so that the lead cannot easily be removed from the vicinity of the reservoir when it is necessary to clean the latter. This has proved to be a disadvantage and we now contemplate (particularly in case a) referred to above) providing the humidifier with a three-pin socket outlet and fitting the supply lead with a three-pin plug for location in the outlet. The kind of plug and socket used on conventional electric kettles is particularly suitable and especially so where these incorporate temperature sensitive arrangements to eject the plug from the socket on the appearance of an unallowable temperature rise.With the arrangement of heater featured under (b) above, the need for a plug and socket connection is less vital since the reservoir can be readily removed, for cleaning purposes, from the electrical heater.

Prior art reservoirs have been made of metal (to ensure good thermal conductivity through the small ring of the reservoir wall around which the heating element was located) but the use of reservoirs formed from a suitably temperature-resistant plastics material is contemplated in accordance with this invention since in this case the area available for heat transfer to the water can be equal to the cross-section of the reser voir. The material known under the Trade name "NORYL" (available from=En gineering Polymers Limited) is particularly suitable.

A humidifier in accordance with this invention can conveniently incorporate the normal safety devices such as a weight sensing switch arrangement in the housing which ensures that the electrical circuit to the electrical heater is only closed when there is a sufficient weight of water in the reservoir to actuate the weight-sensing - switch. The means to ensure that water in the reservoir does not boil can be a conven tional thermostate set to a temperature below 100"C.

One embodiment of silent steam evapora tion humidifier in accordance with the in vention will now. be described, by way of example, with reference to the accompany ing drawing, the sole Figure of which is a schematic sectional side elevation of the first form of humidifier.

In the drawing, the reference numeral 1 designates a cylindrical housing designed to stand on a horizontal surface (e.g. the floor). It is conveniently fabricated from synthetic plastics material (e.g. shockproof polypropylene) and includes a grille la forming an opening in the top of the housing. The precise form of this housing is not important to an understanding of the present invention and will not be further discussed.

Removably located within the housing 1 is a cylindrical open-topped reservoir 2 de signed to be substantially filled with water (typically with volumes of from 6 to 10 litres). A base member 3 is provided below the reservoir water and includes an annular hotplate 6 (typically of power rating in the range 250W to 750W). A microswitch 4 is in circuit with the element of the hotplate 6.

The microswitch is weight-sensitive and requires a given mass of water to be in the reservoir before the element of the hotplate 6 can be energised. 5 is a thermostat (or simmerstat) also in circuit with the element of the hotplate to prevent water in the reservoir from boiling.

The'electric hotplate 6 defines part of the upper surface of the base member 3 and is in good thermal contact with the underside of the base 7 of the reservoir. The reservoir is shown as being removable from the base member 3 but the walls defining the cavity containing the hotplate 6, the switch 4 and the temperature control means 5 may be integral with the walls of the reservoir 2. In this case, to improve the heat conduction to the water, the hotplate 6 can define the base 7 or the base 7 can include one or more metal inserts. The power lead is shown at 8 and is connected to the base element 3 via a plug 9.

To facilitate the slipping of the reservoir 2 over"the base member 3, which includes the hotplate 6, switch 4 and means 5, the cylindrical side wall of the base member may taper inwardly slightly in the upward direction and the skirt portion 2a of the reservoir which depends below the base 7 can taper outwardly in a downward direction. A screw threaded connection between the reservoir and its base member may be achieved by providing cooperating threads on the side wall of the base member and on the skirt.

The heating element can be located in a hollow oil-filled base member 3 and utilise thermal conduction in the oil to transmit heat to a hot plate underlying the base 7.

Making the reservoir 2 removable makes it possible to design a range of reservoirs which differ from one another in the nature of the material used for their fabrication.

This is of particular value when one design of humidifier is to be used with water from widely different regions of the United Kingdom. Serious problems are arising with regard to the increasing levels of solute content in the tap water from different Water Authorities and this coupled with the natural differences in hardness/softness of water from different areas has made it desirable to have a range of different materials for the reservoir and to select the reservoir material with regard to the water with which it is to be used.

Among the preferred materials may be mentioned Stainless Steel (e.g. type 316) INCOLOY 825 (Trade Mark of Henry Wiggins Ltd.) Brass Mild steel or aluminium with a nonmicroporous plastics coating (e.g. an epoxy or acrylic coating) or high temperature resistant plastics material (e.g. polyether sulphone - PES - from ICI) The reservoir is desirably provided with fungicidal properties and a synthetic plastics material with fungicidal properties is preferred for the reservoir 2 of the illustrated embodiment.

WHAT WE CLAIM IS: 1. An evaporation humidifier comprising a housing, an opening in the housing through which water vapour can leave the housing, an open-topped reservoir for water within the housing, an electrical heater for raising the temperature of water in the reservoir and temperature control means to prevent water in the reservoir from boiling, the heater being in the form of a hot plate which underlies a water-supporting surface of the reservoir, which surface is horizontal when the housing is in its normal position for use.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

be equal to the cross-section of the reser voir. The material known under the Trade name "NORYL" (available from=En gineering Polymers Limited) is particularly suitable.

A humidifier in accordance with this invention can conveniently incorporate the normal safety devices such as a weight sensing switch arrangement in the housing which ensures that the electrical circuit to the electrical heater is only closed when there is a sufficient weight of water in the reservoir to actuate the weight-sensing - switch. The means to ensure that water in the reservoir does not boil can be a conven tional thermostate set to a temperature below 100"C.

One embodiment of silent steam evapora tion humidifier in accordance with the in vention will now. be described, by way of example, with reference to the accompany ing drawing, the sole Figure of which is a schematic sectional side elevation of the first form of humidifier.

In the drawing, the reference numeral 1 designates a cylindrical housing designed to stand on a horizontal surface (e.g. the floor). It is conveniently fabricated from synthetic plastics material (e.g. shockproof polypropylene) and includes a grille la forming an opening in the top of the housing. The precise form of this housing is not important to an understanding of the present invention and will not be further discussed.

Removably located within the housing 1 is a cylindrical open-topped reservoir 2 de signed to be substantially filled with water (typically with volumes of from 6 to 10 litres). A base member 3 is provided below the reservoir water and includes an annular hotplate 6 (typically of power rating in the range 250W to 750W). A microswitch 4 is in circuit with the element of the hotplate 6.

The microswitch is weight-sensitive and requires a given mass of water to be in the reservoir before the element of the hotplate

6 can be energised. 5 is a thermostat (or simmerstat) also in circuit with the element of the hotplate to prevent water in the reservoir from boiling.

The'electric hotplate 6 defines part of the upper surface of the base member 3 and is in good thermal contact with the underside of the base 7 of the reservoir. The reservoir is shown as being removable from the base member 3 but the walls defining the cavity containing the hotplate 6, the switch 4 and the temperature control means 5 may be integral with the walls of the reservoir 2. In this case, to improve the heat conduction to the water, the hotplate 6 can define the base

7 or the base 7 can include one or more metal inserts. The power lead is shown at 8 and is connected to the base element 3 via a plug 9.

To facilitate the slipping of the reservoir 2 over"the base member 3, which includes the hotplate 6, switch 4 and means 5, the cylindrical side wall of the base member may taper inwardly slightly in the upward direction and the skirt portion 2a of the reservoir which depends below the base 7 can taper outwardly in a downward direction. A screw threaded connection between the reservoir and its base member may be achieved by providing cooperating threads on the side wall of the base member and on the skirt.

The heating element can be located in a hollow oil-filled base member 3 and utilise thermal conduction in the oil to transmit heat to a hot plate underlying the base 7.

Making the reservoir 2 removable makes it possible to design a range of reservoirs which differ from one another in the nature of the material used for their fabrication.

This is of particular value when one design of humidifier is to be used with water from widely different regions of the United Kingdom. Serious problems are arising with regard to the increasing levels of solute content in the tap water from different Water Authorities and this coupled with the natural differences in hardness/softness of water from different areas has made it desirable to have a range of different materials for the reservoir and to select the reservoir material with regard to the water with which it is to be used.

Among the preferred materials may be mentioned Stainless Steel (e.g. type 316) INCOLOY 825 (Trade Mark of Henry Wiggins Ltd.) Brass Mild steel or aluminium with a nonmicroporous plastics coating (e.g. an epoxy or acrylic coating) or high temperature resistant plastics material (e.g. polyether sulphone - PES - from ICI) The reservoir is desirably provided with fungicidal properties and a synthetic plastics material with fungicidal properties is preferred for the reservoir 2 of the illustrated embodiment.

WHAT WE CLAIM IS: 1. An evaporation humidifier comprising a housing, an opening in the housing through which water vapour can leave the housing, an open-topped reservoir for water within the housing, an electrical heater for raising the temperature of water in the reservoir and temperature control means to prevent water in the reservoir from boiling, the heater being in the form of a hot plate which underlies a water-supporting surface of the reservoir, which surface is horizontal when the housing is in its normal position for use.
2. A humidifier as claimed in claim 1, in

which the opening in the housing is formed in the top thereof and is defined by a grille.
3. A humidifier as claimed in claim 1 or claim 2, in which the electrical heater is located in a base member received in a cavity below the bottom of the reservoir.
4. A humidifier as claimed in claim 1 or claim 2, in which an electrical heater is disposed in a cavity defining a false bottom to the reservoir which false bottom serves at the hot plate.
5. A humidifier as claimed in claim 4, in which the cavity is oil-filled.
6. A humidifier as claimed in any preceding claim, in which a power lead to the heater is connected by a plug and socket located at the reservoir.
7. A humidifier as claimed in any preceding claim, in which the reservoir is formed from synthetic plastics material having fungicidal properties.
8. An evaporation humidifier substantially as hereinbefore with reference to, and as illustrated by, the accompanying drawing.