Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
AUTOMATIC ISOLATING VALVE
Document Type and Number:
WIPO Patent Application WO/2018/185485
Kind Code:
A1
Abstract:
The present invention provides an automatic isolating valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position in which the piston is configured to hold a mechanical isolation switch in an active condition when pneumatic pressure is applied to the piston and a second axial position in which the piston is configured to be withdrawn from the mechanical isolation switch such that the mechanical isolation switch can move to an isolated condition.

Inventors:
KOUTSOS, Theodoros (14 Baynes Place, Waterhouse Business Park, Chelmsford Essex CM1 2QX, CM1 2QX, GB)
Application Number:
GB2018/050912
Publication Date:
October 11, 2018
Filing Date:
April 04, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
REACTON FIRE SUPPRESSION LIMITED (14 Baynes Place, Waterhouse Business Park, Chelmsford Essex CM1 2QX, CM1 2QX, GB)
International Classes:
H01H35/38
Foreign References:
US2327054A1943-08-17
GB2107931A1983-05-05
DE2219933A11973-10-31
Attorney, Agent or Firm:
STRATAGEM IPM LIMITED (Meridian Court, Comberton RoadToft, Cambridge Cambridgeshire CB23 2RY, CB23 2RY, GB)
Download PDF:
Claims:
An automatic pneumatic isolating valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position in which the piston is configured to hold a mechanical isolation switch in an active condition when pneumatic pressure is applied to the piston and a second axial position in which the piston is configured to be withdrawn from the mechanical isolation switch such that the mechanical isolation can move to an isolated condition.

An automatic pneumatic isolating valve according to claim 1, wherein the body comprises a first part for receiving the piston therein and a second part, the second part comprising a connector for connecting the body to an air source.

An automatic pneumatic isolating valve according to claim 2, wherein the first part comprises a first threaded portion and the second part comprises a second threaded portion co-operable with the first threaded portion.

An automatic pneumatic isolating valve according to claim 3, wherein the first threaded portion defines a male thread and the second threaded portion defines a female thread.

An automatic pneumatic isolation valve according to any of claims 2 to 4, wherein the first part of the body defines a cylindrical chamber.

An automatic pneumatic isolation valve according to any of claims 2 to 5, wherein the second part of the body defines an attachment interface co-operable with a tool.

An automatic pneumatic isolation valve according to claim 6, wherein the piston comprises first and second abutment surfaces engageable with the body to constrain axial movement of the piston.

An automatic pneumatic isolation valve according to claim 7, wherein the second part of the body further comprises a third abutment surface engageable with the first abutment surface of the piston when the piston is in the first axial position.

9. An automatic pneumatic isolation valve according to claim 7 or claim 8, wherein the first part of the body further comprises a fourth abutment surface engageable with the second abutment surface of the piston when the piston is in the second axial position.

10. An automatic pneumatic isolation valve according to any of claims 7 to 9, wherein the piston further comprises an annular recess between the first and second abutment surfaces, the annular recess configured to receive an annular seal.

11. An automatic pneumatic isolation valve according to claim 10 further comprising a first seal received in the annular recess of the piston configured to provide a seal between the piston and the first part of the body, a second seal received by the shaft of the piston configured to provide a seal between the second abutment surface of the piston and the fourth abutment surface of the first part of the body, a third seal between the first part of the body and the second part of the body configured to provide a seal therebetween and a fourth seal received by the first part of the body configured to provide a seal between the shaft of the piston and the first part of the body.

12. An automatic pneumatic isolation valve according to any preceding claim, wherein when the piston is in the first position the piston protrudes from the body and when the piston is in the second position the piston is fully contained within the body.

13. An isolation system comprising a pneumatic isolation valve according to any of claims 1 to 12 and a mechanical switch movable axially between a first position in which the mechanical switch is active and a second position in which the mechanical switch is isolated.

14. An isolation system according to claim 13, wherein the mechanical switch comprises a housing that is fastened to the body of the piston.

15. An automatic pneumatic isolating valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position in which the piston is spaced apart from a mechanical isolation switch in an active condition and a second axial position in which the piston is configured to actuate the mechanical isolation switch when pneumatic pressure is applied to the piston. An automatic pneumatic isolation valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position and a second axial position and a mechanical switch movable axially between a first position in which the mechanical switch is active and a second position in which the mechanical switch is isolated, wherein the piston is operable to hold the mechanical switch in the second position when the piston is held in the second axial position by way of external pressure.

Description:
AUTOMATIC ISOLATING VALVE

FIELD The present invention relates to an automatic isolating valve particularly, but not exclusively, for use in conjunction with a mechanical isolator switch.

BACKGROUND Many items of plant machinery and equipment, electrical cabinets and maritime application use mechanical isolation switches to isolate electrical current from either mains power or battery power sources. Mechanical isolation switches come in many standard design formats including button format. In some applications pressing the button of such a mechanical isolation switch causes the electrical connection to break whereas in other applications pressing the button makes the electrical connection and releasing the button breaks the electrical connection.

A common cause of fire in plant and machinery is as a result of a fault with the electrical wiring. Therefore to prevent spread of fire or reignition, it is standard procedure to activate the mechanical isolation switch in the event of a fire to fully isolate power to the plant or machinery. Use of a mechanical isolation switch typically requires manual user intervention. It can take time for a user to reach the switch in the event of an incident that requires electrical isolation.

The present invention seeks to address the aforementioned problems. SUMMARY OF THE INVENTION

An aspect of the invention provides an automatic isolating valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position in which the piston is configured to hold a mechanical isolation switch in an active condition when pneumatic pressure is applied to the piston and a second axial position in which the piston is configured to be withdrawn from the mechanical isolation switch such that the mechanical isolation switch can move to an isolated condition. The present invention provides a means of automatically isolating a mechanical isolation switch using pneumatic pressure to hold the piston against the mechanical isolation switch such that under normal operating conditions the mechanical isolation switch is held in an active condition and an electrical connection is made between a mains or battery power source and an item of plant or machinery. Under abnormal conditions, i.e. upon a heat sensitive tube bursting due to fire or excess heat, the pneumatic pressure is removed from the piston thus enabling the spring force of the mechanical isolation switch to move against the piston into an isolated condition thus breaking the electrical connection between the mains or battery power source and the item of plant or equipment. The plant or equipment can only be re-activated upon application of pneumatic pressure against the piston.

An automatic isolation means is desirable as it reduces the risk of human error associated with isolating an item of plant or equipment during abnormal conditions or inspection and maintenance. Furthermore, upon detection of abnormal operating , i.e. heat or fire, the automatic isolation valve can be promptly activated, i.e. within 1-2 seconds depending on the length of fire/heat sensitive tubing employed within a fire suppression system, by cutting pneumatic pressure thus vastly improving response time for isolation of plant or equipment when a user is not in the immediate vicinity of the mechanical isolation switch. In one embodiment the body comprises a first part for receiving the piston therein and a second part, the second part comprising a connector for connecting the body to an air source.

Manufacture of the automatic pneumatic isolation valve in two parts is advantageous in order to aid assembly of the valve in such a way that the piston can be axially restrained therein.

In one embodiment the first part of the body comprises a first threaded portion and the second part of the body comprises a second threaded portion co-operable with the first threaded portion.

Connecting the first part of the body and the second part of the body via a threaded connection enables the body to be easily disassembled during servicing or replacement.

In one embodiment the first threaded portion defines a male thread and the second threaded portion defines a female thread.

Such a configuration ensures that the thread is effectively an internal thread with no access to the environment. This is advantageous as many items of plant or machinery are used in hostile environments which might see a range of temperatures and humidity or debris particles that could clog an external thread. Use of an internal thread reduces the possibility of damage to the threads. In one embodiment the first part of the body defines a cylindrical chamber. Use of a cylindrical chamber is advantageous so as to provide a curved internal surface that cooperates with piston lubricated o-ring around the piston to prevent the piston sticking. Avoidance of angled axial surfaces is desirable to aid axial movement of the piston relative to the body.

In one embodiment the second part of the body defines an attachment interface co-operable with a tool.

In use, the first part of the body will be fastened to a mechanical switch or to an item of plant or equipment. The design of an automatic isolation valve according to embodiments of the invention is such that the second part of the body can be detached from the first part of the body to access the piston while the first part of the body remains in place. Provision of an attachment interface co- operable with a tool is thus desirable to facilitate removal and replacement of the second part of the body.

In one embodiment the piston comprises first and second abutment surfaces engageable with the body to constrain axial movement of the piston.

Movement of the piston requires limiting axially to ensure that it can only move as far as is necessary to perform its desired function, i.e. a maximum distance of approximately 8mm.

In one embodiment the second part of the body further comprises a third abutment surface engageable with the first abutment surface of the piston when the piston is in the second axial position.

Such a configuration ensures that the piston can only ever be a maximum pre-determined distance away from the mechanical isolation switch when pneumatic pressure is activated. This is important as the greater distance the piston has to travel towards the mechanical isolation switch the higher the risk of the valve failing. Limiting the distance that the piston is required to travel to within known tolerances negates this risk.

In one embodiment the first part of the body further comprises a fourth abutment surface engageable with the second abutment surface of the piston when the piston is in the first axial position. Provision of the abutment surface between the first part of the body and the piston effectively provides a secure seat against which the piston is urged when pneumatic pressure is applied. The seat limits how far the piston can travel towards the mechanical isolation switch such that when pneumatic pressure is applied the piston will reliably engage the mechanical isolation switch to make an electrical connection between a mains or battery power source and an item of plant or equipment.

In one embodiment the piston further comprises an annular recess between the first and second abutment surfaces, the annular recess configured to receive an annular seal.

The annular recess provides a seat for an annular seal that provides one of three seals between the piston and the body to prevent leakage of air from the chamber defined by the body.

In one embodiment the valve comprises a first seal received in the annular recess of the piston configured to provide a seal between the piston and the first part of the body, a second seal received by the shaft of the piston configured to provide a seal between the second abutment surface of the piston and the fourth abutment surface of the first part of the body, a third seal between the first part of the body and the second part of the body configured to provide a seal therebetween and a fourth seal received by the first part of the body and configured to provide a seal between the shaft of the piston and the first part of the body.

The first, second and fourth seals provide seals between the piston and the body to prevent leakage of air and thus unplanned activation of the valve. The third seal provides a seal between the two parts of the body for the same purpose. Each potential leak path is sealed by at least a dual seal arrangement to reduce the risk of air leakage as far as is possible.

In one embodiment when the piston is in the first position the piston protrudes from the body and when the piston is in the second position the piston is fully contained within the body. Another aspect of the invention provides an automatic pneumatic isolation valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position in which the piston is configured to hold a mechanical isolation switch in an active condition when pneumatic pressure is applied to the piston and a second axial position in which the piston is configured to be withdrawn from the mechanical isolation switch such that the mechanical isolation switch moves to an isolated condition when pneumatic pressure is removed from the piston and a mechanical switch movable axially between a first position in which the mechanical switch is active and a second position in which the mechanical switch is isolated. Another aspect of the invention provides an automatic pneumatic isolation valve comprising a body configured to receive a piston axially therein, the piston being movable within the body between a first axial position and a second axial position and a mechanical switch movable axially between a first position in which the mechanical switch is active and a second position in which the mechanical switch is isolated, wherein the piston is operable to hold the mechanical switch in the second position when the piston is held in the second axial position by way of external pressure.

FIGURES

The invention will now be described by way of reference to the following figures:

Figure 1 shows an isometric view of an assembly comprising an automatic isolation valve and a mechanical isolation switch housing;

Figure 2 shows an exploded view of the assembly of figure 1;

Figure 3 shows an exploded view of the body and piston of the assembly of figures 1 and 2; Figure 4 shows an external view of the assembly with the piston in its first axial position; Figure 5 shows a cross-section through the assembly of figure 4;

Figure 6 shows an external view of the assembly with the piston in its second axial positon; Figure 7 shows a cross-section through the assembly of figure 6.

DESCRIPTION The figures show various views of an automatic isolating valve 10 according to embodiments of the invention. In use, the automatic isolating valve 10 is combined with a mechanical isolating switch (not shown) that is shrouded by a housing 100. The automatic isolating valve 10 comprises a body 12 formed from a first part 14 and a second part 16. The first part 14 of the body 12 defines a first end 14a and a second end 14b. The first end 14a is defined by an internal female thread 14c and is tapered to aid alignment of the second part 16 of the body 12 with the first part 14 of the body 12. The second end 14b is open and configured to receive a part of the mechanical isolating switch housing 100. The first part 14 of the body 12 is secured to the mechanical isolating switch housing 100 by way of three fasteners 18a, 18b. The two smaller fasteners 18a shown in the figures are used to drive the automatic isolating valve 10 into position when applied to the mechanical switch. The larger fastener 18b is used to lock the automatic isolating valve onto the shaft of a mechanical switch. The fasteners 18a, 18b thus align and stabilise the automatic isolating valve 10. To remove the automatic isolating valve from its operating position the following operations would need to occur: i) the automatic isolation valve is depressurised; ii) the larger fastener 18b is released; and the automatic isolating valve 10 is twisted and pulled axially to remove. In other embodiments the body 12 might be received by a part of a mechanical isolating switch housing 100. Internally, the first part 14 of the body 12 is split into two chambers 20, 22 by an annular projection 24. Each chamber comprises a machined bore sized to receive a respective part of a piston 26. The chamber 20 adjacent to the first end 14a of the first part 14 of the body 12 is further defined by a shoulder 28 adjacent to its upper end which is configured to act as a stop against which the second part 16 of the body 12 engages against in use. The chamber 22 adjacent to the second end 14b of the first part 14 of the body 12 is further defined by an annular recess 30 configured to receive a seal 32 for providing a seal between the second part 16 of the body 12 and the piston 26.

The second part 16 of the body 12 comprises a male threaded portion 16a that is configured to screw into the internal female thread 14c of the first part 14 of the body 12 and a machined portion 16b configured for engagement with a tool to rotate the second part 16 of the body 12 relative to the first part 14 of the body 12. A seal 38 is provided on the threaded portion 16b to provide a seal between the threaded portion 16b and the internal female thread 14c. The machined portion 16b comprises diametrically opposed flat spots 16c for engagement with a spanner. The second part 16 of the body 12 further comprises an axial air port 16d therethrough which is internally threaded to receive a connector 16e for connecting the second part 14 of the body 12 to an air source. The underside 16f of the threaded portion 16a of the second part 16 of the body 12 defines an abutment surface configured for abutment with a portion of the piston 26 as will be described further below. The piston 26 comprises a cylindrical shaft 26a and a machined flange 26b including a planar upper and lower face, each defining a respective abutment surface 26c, 26d, and an annular recess 26e configured to receive a seal 34 for providing a seal between the machined flange 26b and the first part 14 of the body 12. The abutment surface 26c of the machined flange 26b of the piston 26 abuts the abutment surface 16f of the second part 16 of the body 12 when the piston is positioned in its uppermost axial positon with respect to the body 12. The abutment surface 26d of the machined flange 26b of the piston 26 abuts the uppermost surface of the annular projection 22 of the second part 14 of the body 12 when the piston 26 is in its lowermost axial position with respect to the body 12. A further seal 36 is provided on the shaft 26a of the piston 26 and provides a seal between the shaft 26a of the piston 26 and the annular projection 22 of the second part 14 of the body 12.

In use, the automatic isolating valve 10 is connected to compressed gas source (not shown) by way of the connector 16e. When the compressed gas source is activated, an inert gas is introduced through the axial port 16d and urged against the abutment surface 26b of the piston 26 at approximately 15 bar to drive the piston 26 downwards into its lowermost position with respect to the body 12. In its lowermost position the piston 26 engages with a push button type mechanical isolation switch to make an electrical connection between a power source and an item of plant or equipment. When the compressed gas source is deactivated for any reason, for example upon bursting of fire/heat sensitive tubing in the vicinity of a fire, the piston 26 is no longer urged against the mechanical isolation switch and the spring strength of the mechanical isolation switch is such that it overcomes any residual pressure provided by the piston 26 and breaks the electrical connection between the mains or battery power source and the item of plant or equipment. The foregoing description of the invention is an example only and is not intended to limit the scope of the claims in any way. It will be appreciated that the foregoing description is just one way of putting the invention into effect. In particular, it will be appreciated that embodiments of the invention could use a hydraulic system or electric motor to actuate the piston.




 
Previous Patent: AUTOMATIC VALVE

Next Patent: COLOUR CHANGING COMPOSITIONS