GB2137349A

GB2137349A - Discharge valve controlled by liquid level sensor

Info

Publication number: GB2137349A
Application number: GB08407844A
Authority: GB
Inventors: Elvio Bernardi; Antonio Pirone
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-28
Filing date: 1984-03-27
Publication date: 1984-10-03
Also published as: GB8407844D0; FR2543657A1; SE8401692D0; IT1158850B; ES531070A0; IT8367340A0; GB2137349B; FR2543657B3; SE8401692L; ES8503815A1; JPS59217076A; DE3411153A1

Abstract

An automatic valve (1) assembly for draining condensate in compressed air systems, comprises electric means (8, 10) for detecting water in a condensate collecting tank; the said means activating an electrovalve (5) for draining off the said condensate when the liquid level exceeds a predetermined valve. <IMAGE>

Description

SPECIFICATION Automaticvalvefordraining condensate on com pressed air systems The present invention relates to an automatic valve for draining condensate on compressed air systems.

Awell known requirement of compressed air systems is that of regular draining to remove conde nsate usually collected in a collecting tank. Provision has formerly been made for automatic condensate draining valves usually comprising a float assembly for controlling opening of the valve.

The aim of the present invention is to provide an automatisvalve fordraining condensate on compressed air systems that is relatively easy, and therefore cheap to make, easier to fit and more compactthan known types of automatic drain valves.

With these aims in view, the present invention relates to an automaticvalve for draining condensate on compressed air systems, characterised by the fact that it comprises first electric means for detecting a preset water level in a condensate collecting tank, the said first means activating an electrovalvefor draining off the said condensate.

A preferred arrangementofthe present invention will now be described, byway of a non-limiting example, with reference to the attached drawings in which: Fig. 1 shows an electric diagram of an automatic drain valve according to the present invention; Fig. 2 shows a rough construction diagram of the automatic valve in Fig. 1.

Number 1 in Fig. 1 indicates the said automatic valve, enclosed by the dotted line and comprising two a.c. mains voltage supply terminals (3), in this case 220V, one connected to the anode of diode 4the cathode of which is connected to a terminal of electrovalve Sthe other terminal ofwhich is connected to the anode of silicon controlled diode (SCR) 6 the cathode of which is connected to the otherterminal 3.

The anode of controlled diode 6 is connected, via resister7,toafirstconducting electrode (8), while the control electrode of diode 6 is connected, via resistor 9, to a second conducting electrode (10). The terminals ofthe said resistors 7 and 9 towards electrodes 8 and 10 are also connected to two electrodes, 12 and 13 respectively.

As shown in Fig. 2, the said automatiovalve (1) comprises a casing (20) housing the elements shown in Fig. 1. In more detail, the said casing (20) has a tubular portion (21) extending upwards and suitably threaded for connection to a bottom hole (22) on tank 23 which is only partially shown and of the known type for collecting condensate. Inside tank 23, the two electrodes (8, 10) projectfrom the said portion 21 which, internally, forms a duct (25) for external .drainage and on which electrovalve 5 is fitted.

Electrodes 12 and 13 are fitted on to a side face (26) of casing 20 which is also connected with a cable (28) for supplying terminals 3. Operation of the automatic drain valve covered by the present invention is as follows. By means of portion 21, casing 20 is fitted inside hole 22 on tank 23 so as to arrange electrodes 8 and 10 at a preset level inside tank 23. When the condensate collected inside tank 23 reaches the said preset level, thus causing conduction between electrodes 8 and 10, the spark circuit of controlled diode 6 is sparked. To do this, a current of as little as 300 uA is sufficient. The resulting half-wave conduction of controlled diode 6 activates electrovalve 5 which, in turn, opens duct 25 for draining out the condensate.

When the said condensate has been drained off, electrodes 8 and 10 are again isolated so as to close electrovalve 5.

The user can easily check operation ofvalve 1 by placing a finger between electrodes 12 and 13 which sparks the spark circuit of controlled diode 6 so as to activate electrovalve 5.

The advantage of the automatic drain valve covered by the present invention is that it provides for a fairly straightforward device which is cheap to make on account of the small number of components involved, all of which are readily available on the market. What is more, casing 20 is easily fitted into hole 22 on tank 23 with no need for cumbersome devices.

To those skilled in the art it, will be clearthat changes can be made both to the Fig. 1 circuit layout and Fig. 2 arrangement of the automatic drain valve described and illustrated herein without, however, departing from the scope of the present invention. For example, to prevent galvanic corrosion of electrodes 8 and 10,they may be made of conducting elastomer material.

Furthermore, in special applications in which, instead of a bottom drain hole (22), condensate collecting tank 23 is provided with an internal pipe sucking up from the bottom and coming out roughly halfway up tank 23, if tubular portion 21 is fitted inside the said hole halfway up the tank, the circuit between electrodes 8 and 10 will fail to close, even with water inside tank 23, and drain electrovalve 5 will fail to be activated. The automatic drain valve covered by the present invention, however, operates correctly with the additional circuitry shown by the dotted line in Fig.

1 wherebythe cathode of diode 4 is connected to the anode of diode 30 the cathode of which is connected to a condenser (31) series connected to a resistor (32), in turn, connected to the control electrode of diode 6.

Supply terminals 3 are also connected parallel to the supply of operating means (the electric motor on the compressor) on the said compressed air systems.

Thus, when the said operating means are activated, diode 6 is conducted, via diode 30; condenser 31 and resistor32, for an initial transient period, determined by the charge constant of condenser 31,during which drain electrovalve 5 is opened. If tank 23 contains no condensate, electrodes 8 and 10 are isolated so that, at the end ofthe said transient period, diode 6 is de-activated and electrovalve 5 closed. If, on the other hand, the tank contains condensate, the pressure exerted bythe compressor sucks the condensate up fromthe bottom oftank 23 through the internal pipe and up to electrodes 8 and 10 which, in this case, keep electrovalves 5 open until all the condensate has been drained out.

Claims

1. Automatic valve for draining condensate on compressed air systems, characterised by the fact that it comprises first electric means for detecting water in a condensate collecting tank, the said first means activating an electrovalvefordraining the said condensate.

2. Valve according to Claim 1, characterised bythe factthatthe said first means comprise a pair of conducting electrodes.

3. Valve according to Claim 1 or 2, characterised by the fact that the said first means activate semiconducting devices activating the said electrovalve; the said semi-conducting devices comprising a silicon controlled diode (SCR) and the said first means being connected to the spark circuit of the said diode.

4. Valve according to Claim 3, characterised by the factthatthe said electrovalve is supplied with a.c.

mains voltage via the said semi-conducting devices.

5. Valve according to any one of the foregoing Claims,characterised bythefactthatitcomprises second electricmeansforpreliminaryactivation of the said drain electrovalve when the said compressed air systems are started up; the said second means being activefora preset initial transient period,

6. Valve according to Claim 5 and dependant on Claim 3 or4, characterised by the factthatthe said second means are connected to the spark circuit ofthe said diode and are supplied at the same time as the operating means on the said systems.

7. Valve according to Claim 5 or 6, characterised by thefactthatthe said second means comprise at least a series connected diode, condenser and resistor.

8. Valve according to any one of the foregoing Claims, characterised by the fact that it comprises a casing housing the said first and second means ofthe said electrovalve and the relative connected circuit means; the said casing having a first portion designed to connect with a corresponding portion affording access to the inside of the said tank; the said first electric detecting means being housed in the said first portion and the said casing also comprising a communicating duct controlled by the said electrovalve and designed to drain out the said first portion.

9. Valve according to Claim 8, characterised by the fact that the said first electric detecting means project inside the said tank at a preset level.

10. Valve according to either of Claims 8 or 9, characterised by the fact that the said casing has a second portion fitted with third electric means for activating the said electrovalve and arranged parallel tothe saidfirst electric detecting means.

11. Valve according to Claim 10, characterised by thefactthatthe said third electric means comprise a pair of electrodes to which access is made available for manual contact.

12. Automatic valve for draining condensate in compressed air systems substantially as hereinbefore described with reference to the accompanying draw ings.