JP2007032844A - Float type valve device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a float type valve device capable of effectively preventing galvanic corrosion caused by abutting of a valve element on a valve seat while simplifying a structure of the device. <P>SOLUTION: This float type valve device is constituted by providing the valve seat 11 forming a valve port 11a opened for a valve chamber 4 in the valve chamber 4 in which gas S and liquid W flow through a flow-in passage 8a, providing the float type valve element 12 opening and closing the valve port 11a by leaving the valve seat 11 or being seated on the valve seat 11 by travel in a condition in which it floats in the liquid W in the valve chamber 4 interiorly, and discharging either of gas S and liquid W from the valve chamber 4 through the valve port 11a selectively. A valve element abutting part 11A of the valve seat 11 is formed by a metal being more electropositive in natural potential than the metal forming the valve element 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a steam type valve device used as a steam trap for discharging condensate from a steam system, an air trap for discharging condensate from a compressed air system, or an air vent for discharging air from a water piping system,
Specifically, a valve seat in which a valve opening that opens to the valve chamber is provided in the valve chamber into which gas and liquid flow through the inflow passage, and the valve seat is separated from the valve seat by moving in a state of floating in the liquid. A float-type valve body that opens and closes the valve port is built in the valve chamber, and one of gas and liquid is selectively discharged from the valve chamber through the valve port by opening and closing the valve port by the valve body. The present invention relates to a float type valve device.

  Conventionally, in this type of float type valve device, a metal member that acts as a sacrificial anode to prevent galvanic corrosion (local corrosion due to contact of dissimilar metals) caused by contact between the valve seat and the valve body (that is, There is one in which a base metal member having a lower natural potential than apparatus components such as a valve body and a valve seat is attached inside a valve case (see Patent Document 1 below).

JP-A-57-76398

  However, in the above-described conventional device, a metal member as a sacrificial anode, which is different from the device components such as the valve body and the valve seat, is additionally attached to the inside of the valve case, so that the number of parts is increased and the device structure is complicated. However, there has been a problem that the apparatus is increased in size, which increases the cost of the apparatus.

  In addition, since the metal member as the sacrificial anode is consumed due to sacrificial corrosion, it is necessary to replace the metal member as the sacrificial anode with a new one in a timely manner, which increases the maintenance burden. In particular, the size of the metal member as a sacrificial anode is limited when accommodated in the valve case, but the size of the base metal in galvanic corrosion increases as the area of the base metal decreases. The consumption of the metal member as the limited sacrificial anode is considerably fast and the frequency of maintenance becomes high, and this also increases the burden of maintenance.

  In view of this situation, the main problem of the present invention is to effectively solve the above problems by preventing galvanic corrosion with a rational method.

[1] A first characteristic configuration of the present invention relates to a float type valve device,
In the valve chamber into which gas and liquid flow in through the inflow path, a valve seat is formed that forms a valve opening that opens to the valve chamber.
A float-type valve element that opens and closes the valve port by moving away from the valve seat by moving in a liquid floating state is provided in the valve chamber,
In the float type valve device configured to selectively discharge one of gas and liquid from the valve chamber through the valve port by opening and closing the valve port by the valve body,
The valve body contact portion of the valve seat is formed of a metal having a natural potential higher than that of the metal forming the valve body.

  That is, in the float type valve device, the valve element abutting portion of the valve seat (that is, the portion where the seated valve element abuts) is considerably smaller than the valve element that needs to ensure buoyancy. However, according to the first feature, the metal that forms the valve body contact portion of the valve seat is a noble metal than the metal that forms the valve body. Even if galvanic corrosion occurs due to contact between the valve body and the valve body, the corrosion occurs on the valve body side, and this causes galvanic corrosion caused by contact with the valve body to occur on the valve body contact portion of the valve seat. It can be prevented almost certainly.

  In addition, in the valve seat (particularly around the valve opening), the exhausted fluid to the valve opening passes through the gap between the valve body and the valve seat with the valve body slightly away from the valve seat, so that erosion, etc. There is also a tendency that the exhaustion of the valve seat is further accelerated due to the synergy between the mechanical exhaustion and the galvanic corrosion. By effectively preventing galvanic corrosion at the valve, acceleration of valve seat consumption due to synergy between mechanical wear and galvanic corrosion can also be effectively suppressed. It is possible to effectively prevent fluid leakage (that is, fluid leakage that should be prevented by closing the valve opening by the valve body).

  And even if the valve body contact portion of the valve seat is formed of a metal that is more precious than the metal that forms the valve body in this way, the valve body has a sufficient valve buoyancy to ensure sufficient buoyancy as described above. Because the surface area is much larger than the contact part, the valve body is unlikely to galvanically corrode in contact with the valve seat, and the metal and valve body forming the valve body contact part of the valve seat are formed. If the difference in natural potential with the metal to be used is kept within a certain range in the selection of both metals, the galvanic corrosion on the valve body caused by contact with the valve seat should be suppressed to the extent that there is no practical problem. Can do.

  That is, according to the first characteristic configuration, the galvanic corrosion caused by the contact between the valve seat and the valve body can be prevented for both the valve body contact portion and the valve body of the valve seat as described above, A metal member as a sacrificial anode other than the device component such as a valve seat can be additionally eliminated from the inside of the valve case, which reduces the number of parts compared to the above-described conventional device. , Simplification of the structure of the apparatus, miniaturization of the apparatus, etc., which can reduce the cost of the apparatus and eliminate the need to replace the metal member as a sacrificial anode. The burden of maintenance can be reduced effectively.

  Incidentally, in order to prevent the galvanic corrosion caused by the contact between the valve seat and the valve body while omitting the additional mounting of the metal member as a sacrificial anode, the metal and valve forming the valve body contact portion of the valve seat It is also conceivable to use a metal having a natural potential equal to the metal forming the body. However, in this case, the choice of both metals is limited in the design of the device, and there arises a problem that it is difficult to obtain functions required for the valve seat and the valve body in terms other than prevention of galvanic corrosion. According to one feature configuration, the problem of such metal options can be reduced.

  In the implementation of the first characteristic configuration, the valve body may be hollow inside or non-hollow inside. When the outer surface portion and the inside of the valve body are formed of different materials, Alternatively, only the outer surface portion of the valve body may be formed of a base metal having a natural potential as compared with the valve body contact portion of the valve seat.

  The valve seat may be either one in which the entire valve seat including the valve body abutting part is formed of the same metal, or one in which the valve body abutting part and the other part of the valve seat are formed of different materials, In this case, an electrical insulating material may be interposed at an appropriate place as necessary.

  In addition, the metal that forms the valve contact portion of the valve seat may be either a single element metal or an alloy.

[2] The second characteristic configuration of the present invention specifies an embodiment suitable for the implementation of the first characteristic configuration.
The difference in natural potential between the metal forming the valve body contact portion of the valve seat and the metal forming the valve body is 0.4 V vs SCE or less.

  In other words, according to this second characteristic configuration, while adopting the above-described configuration in which the valve body abutting portion of the valve seat is formed of a noble metal than the valve body, on the valve body side caused by the contact with the valve seat. The galvanic corrosion of the valve seat can be almost certainly suppressed to the extent that there is no problem in practical use, and as a result, the galvanic corrosion caused by the contact between the valve seat and the valve body can be prevented. The intended purpose of preventing both can be achieved more reliably and effectively.

  In the implementation of the first or second characteristic configuration, the valve body may be configured to permit the rotation operation of the valve body in a state of floating in the liquid.

  With the above configuration, the rotation operation of the valve body in a state of floating in the liquid is allowed, so that the contact portion of the valve seat on the surface of the valve body is changed by the rotation operation (in other words, the valve seat The contact portion is not limited to one point on the surface of the valve body), so that the valve body is formed of a base metal rather than the valve body contact portion of the valve seat. Galvanic corrosion on the valve body side due to contact with the valve seat can be more effectively prevented, and galvanic corrosion caused by contact between the valve seat and the valve body can be prevented with the valve body contact portion of the valve seat. The intended purpose of preventing both the valve body and the valve body can be achieved more reliably and effectively.

  In addition, the rotation operation of the valve body permitted in the implementation of the above configuration may be either a rotation operation around a specific rotation axis or a rotation operation in which the rotation axis direction is indefinite. The rotation angle is not limited to a free rotation operation that exceeds 360 degrees, but may be a rotation operation that allows an allowable rotation angle to be limited to less than 360 degrees.

  Further, for example, a configuration in which the rotation operation of the valve body is actively promoted by gas or liquid flowing into the valve chamber may be employed.

[3] The third characteristic configuration of the present invention specifies an embodiment suitable for the implementation of the first or second characteristic configuration.
The valve chamber is provided with a support seat that contacts the valve body and supports the valve body together with the valve seat while the valve body is seated on the valve seat.

  That is, according to the third characteristic configuration, the valve body is supported by the valve seat and the support seat in the seated state on the valve seat (that is, the state in which the valve port is closed). Compared to the case where the valve body is supported only by the valve seat, the valve body can be kept in a more stable seating state, and a minute amount between the valve body and the valve seat due to the unstable seating state of the valve body. It is possible to effectively prevent the gap from being formed indefinitely.

  By preventing the formation of such indefinite minute gaps, it is possible to prevent mechanical wear such as erosion from occurring in the valve seat due to the high-speed flow passing through the minute gaps. Combined with preventing galvanic corrosion on the valve seat due to contact with the body, the durability of the valve seat can be improved more effectively, and fluid leakage caused by exhaustion of the valve seat is also more effective Can be prevented.

[4] The fourth characteristic configuration of the present invention specifies an embodiment suitable for the implementation of the third characteristic configuration.
The two support seats are arranged in a state in which the axial line between the two support seats and the central axis of the valve seat are in a torsional positional relationship, and the valve body is formed by the two support seats and the valve seat. The point is that the structure is supported at three points.

  In other words, according to the fourth characteristic configuration, the valve body is supported by the three-point support by the two support seats and the valve seat in the seated state on the valve seat. For example, the valve body is seated on the valve seat. Can be maintained in a more stable seating state compared to a case where the valve body is supported by two-point support by a single support seat and a valve seat, and the valve body and It is possible to more effectively prevent a minute gap from being indefinitely formed between the valve seat and the valve seat.

  Therefore, mechanical wear such as erosion caused by high-speed flow passing through such an uncertain minute gap can be more effectively prevented from occurring in the valve seat, thereby improving the durability of the valve seat. Can be more effectively improved, and fluid leakage caused by exhaustion of the valve seat can be further effectively prevented.

[5] The fifth feature configuration of the present invention specifies an embodiment suitable for the implementation of the third or fourth feature configuration.
The valve body contact portion of the support seat is formed of a metal having a lower natural potential than the metal forming the valve body, or a metal having a natural potential equal to or substantially equal to the metal forming the valve body. It is in.

  That is, in this fifth characteristic configuration, when the valve body contact portion of the support seat is formed of a base metal having a natural potential rather than the metal forming the valve body, the galvanic corrosion is caused by the contact between the support seat and the valve body. However, the corrosion occurs on the side of the support seat. Further, when the valve contact portion of the support seat is formed of a metal having a natural potential equal to or substantially equal to the metal forming the valve body, galvanic corrosion caused by the contact between the support seat and the valve body is caused on the valve body side and Both sides of the support seat can be prevented.

  That is, in any case, galvanic corrosion caused by the contact between the support seat and the valve body can be prevented from occurring on the valve body side. It is possible to more effectively achieve prevention of galvanic corrosion on the valve body side while adopting the above-described configuration forming the body, and galvanic corrosion is performed on both the valve body contact portion and the valve body of the valve seat. It is possible to achieve the intended purpose of preventing the occurrence more reliably and effectively.

  In the implementation of the fifth characteristic configuration, the support seat is formed of the same metal as the entire support seat including the valve body abutting portion, or the valve body abutting portion and the other portion of the support seat are formed of different materials. In either case, an electrical insulating material may be interposed at an appropriate place as necessary.

  FIG. 1 shows a free float type steam trap. In this steam trap, a bowl-shaped inlet side outer case member 2 in which a bowl-shaped strainer 1 is stretched, and a bowl-shaped inner case member 3 are also provided. A valve chamber 4 is formed between the strainer 1 and the inner case member 3 in the connected body by integrally connecting the opening edges with each other in an airtight manner by welding or the like. An inlet chamber 5 communicating with the valve chamber 4 through a large number of holes is formed between the strainer 1 and the inlet side outer case member 2.

  Further, the inner case member 3 and the outlet side outer case member are integrally connected to the inner case member 3 by welding or the like so as to cover the inner case member 3 from the outside. 6 and an internal discharge path 7 is formed.

  That is, a valve case C that forms an outer shell of the steam trap is formed by the outer case members 2 and 6 on the inlet side and the outlet side and the externally exposed portion of the inner case member 3, and the inlet chamber 5 is formed inside the valve case C. The valve chamber 4 and the internal discharge path 7 are partitioned.

  The inlet-side outer case member 2 is provided with an inlet-side pipe connecting portion 8 that forms an inflow passage 8a for the steam S and condensate W, and the outlet-side outer case member 6 has a condensate W. An outlet side pipe connection portion 9 that forms the outflow passage 9 a is provided, the inflow passage 8 a communicates with the upper portion of the inlet chamber 5, and the outflow passage 9 a communicates with the upper portion of the internal discharge passage 7.

  The valve chamber 4 is provided with a cylindrical valve seat 11 formed around a valve port 11a that opens obliquely upward with respect to the valve chamber 4 in the lower portion of the valve chamber. The valve chamber 4 communicates with the lower part of the internal discharge passage 7 through the cylindrical hole 11b of the valve seat 11 serving as a throttle opening (in other words, an orifice) and floats on the condensate W in the valve chamber 4 (rotating shaft). In a floating state in which rotation of the core is indefinite) is allowed to descend as the condensate water level in the valve chamber 4 is lowered and is seated on the valve seat 11 (shown by a solid line). A sealed hollow spherical float valve body 12 that rises with the rise of the condensate water level and separates from the valve seat 11 (indicated by a one-dot chain line) is provided in the valve chamber 4.

  That is, when the steam S and its condensate W flow into the valve chamber 4 through the inlet chamber 5 and the strainer 1 from the inflow passage 8a, the valve port 11a is closed by the seating of the float valve body 12 on the valve seat 11. Further, the steam S and condensate W in the valve chamber 4 are prevented from being discharged to the outside through the valve port 11a, the internal discharge passage 7, and the outflow passage 9a, and the float valve body 12 is separated from the valve seat 11. By opening the valve port 11a, only the condensate W (that is, the condensate whose water level has risen) in the valve chamber 4 is discharged to the outside through the valve port 11a, the internal discharge channel 7, and the outflow channel 9a.

  Reference numeral 13a denotes a support seat that supports the float valve body 12 together with the valve seat 11 by contacting the lower portion of the float valve body 12 with the float valve body 12 seated on the valve seat 11. As shown in FIGS. 1 and 2, it is formed at the tips of two support fingers 13d that are integrally extended in a hook shape from an annular base portion 13c in which a mounting hole 13b of the valve seat 11 is formed.

  Further, these two support seats 13a are arranged in such a state that the shaft core x connecting the support seats 13a is in a torsional positional relationship with the central shaft core p of the valve seat 11, and thereby the float in the seated state The valve body 12 is stably supported at three points by the valve seat 11 and the two support seats 13a.

  Reference numeral 14 denotes a bimetal, and the bimetal 14 is not in contact with the float valve body 12 whose tip is seated when the valve chamber 4 is hot (that is, during normal use in which steam S and condensate W flow in). When the bent valve body 12 is allowed to be seated on the valve seat 11 as shown in the same figure, while cold air or cold water flows into the valve chamber 4 and the valve chamber 4 becomes cold. The leading end of the float valve element 12 that pushes up the seated float valve body 12 is stretched and refracted, and the seated float valve element 12 is forcibly separated from the valve seat 11, thereby allowing cold air or low temperature water to flow through the valve port 11 a. Drain from chamber 4.

  The annular base portion 13c of the support seat 13a is attached to the inner case member 3 by being fitted into an attachment hole 15 formed in the inner case member 3, and the valve seat 11 is fitted into the mounting hole 13b of the annular base portion 13c. Further, the valve seat 11 includes a truncated cone-shaped tip member 11A that forms a valve body abutting portion with which the seated float valve body 12 abuts, and an annular base portion 13c. It is formed with a cylindrical main body member 11B that fits into the mounting hole 13b, and the tip member 11A is attached to the main body member 11B by fitting into a mounting hole 11c formed in the front surface of the main body member 11B.

  The inlet side and outlet side case members 2 and 6 and the inner case member 3 forming the valve case C are made of high strength metal (for example, SUS13, SUS316L, FCD450, etc.), and the float valve body 12 is high strength. In addition, it is formed of a metal (for example, SUS316L or SUS304) having excellent corrosion resistance and wear resistance. On the other hand, as shown in FIG. The tip member 11 </ b> A (valve element contact portion) is made of a noble (higher) metal having a natural potential than the metal forming the float valve element 12.

  That is, by forming the tip member 11A of the valve seat 11 (in other words, the portion around the valve port 11a) with a metal nobler than the metal forming the float valve body 12, the float valve body 12 and the valve seat 11 Galvanic corrosion caused by the contact between the float valve body 12 and the valve seat 11 with the float valve body 12 slightly away from the valve seat 11 is prevented. Preventing mechanical exhaustion such as erosion around the valve port 11a of the valve seat 11 from being accelerated in synergy with galvanic corrosion by passing the condensate W discharged to the valve port 11a at a high speed through the gap therebetween, Thereby, the durability of the valve seat 11 is improved, and the fluid leakage caused by the exhaustion of the valve seat 11 (that is, the steam leakage that should be prevented from being discharged from the valve chamber 4 due to the closure of the valve port 11a by the float valve body 12). ) Effectively prevent It is to be.

  Note that the difference in natural potential between the metal forming the float valve body 12 and the metal forming the tip member 11A of the valve seat 11 is within a certain range (desirably 0.4 V vs. SCE or less, more desirably). Therefore, the float valve body 12 is larger than the valve seat 11 and is less susceptible to galvanic corrosion than the valve seat 11, and the float in the floating state to the condensate W The tip of the valve seat 11 is coupled with the fact that the contact portion of the valve seat 11 on the outer surface of the float valve body 12 changes due to the rotation of the valve body 12 and the galvanic corrosion hardly occurs on the float valve body 12. Galvanic corrosion on the side of the float valve body 12 caused by contact with the member 11A (that is, a noble metal) is also suppressed to the extent that there is no practical problem.

  Various metals (for example, SUS420F, SUS316L, SUS303, SCS16) may be used for the metal forming the main body member 11B of the valve seat 11 and the metal forming the integral part of the support seat 13a, the support finger 13d, and the annular base portion 13c. In order to prevent galvanic corrosion of the float valve body 12 due to contact between the float valve body 12 and the support seat 13a, the metal that forms the support seat 13a (particularly the valve body contact portion) is used. It is desirable to use a metal whose natural potential is lower (lower) than the metal forming the float valve body 12 or a metal whose natural potential is equal to or substantially equal to the metal forming the float valve body 12.

  Further, in forming the steam trap shown in the present embodiment, an appropriate place (for example, a contact portion between the tip member 11A and the main body member 11B in the valve seat 11 or the main body member 11B and the support seat 13a of the valve seat 11 is formed as necessary. It is desirable to interpose an electrical insulator in a contact portion with the annular base portion 13c.

[Another embodiment]
Next, another embodiment will be listed.
In the above embodiment, the float valve body 12 is lowered as the condensate water level in the valve chamber 4 is lowered to close the valve port 11a, and the float valve body 12 is raised as the condensate water level in the valve chamber 4 is raised. An example in which the present invention is applied to a float type steam trap that opens the valve port 11a is shown. However, the present invention relates to a float type steam trap as shown in FIG. The present invention can also be applied to a steam trap of a type in which the float valve body 12 is raised to close the valve port 11a and the float valve body 12 is lowered to open the valve port 11a as the steam flow into the valve chamber 4 stops.

  That is, in the float type steam trap shown in FIG. 4, the float valve body 12 is formed into a hollow partial sphere having a lower opening 12a, and a small hole 12b for removing steam is formed at the top of the float valve body 12. It is. Further, the jet pipe 16 that jets the steam S and the condensate W flowing in from the inflow passage 8a into the float valve body 12 from the upper jet hole 16a is connected to the inside of the float valve body 12 from the lower opening 12a of the float valve body 12. It is erected in the valve chamber 4 in a state of entering into the valve chamber 4.

  And the valve seat 11 and the support seat 13a are arrange | positioned at the upper part of the valve chamber 4, By this structure, when the vapor | steam S flows in from the inflow path 8a, the inflow vapor | steam S is sent from the upper end ejection hole 16a of the ejection pipe 16. By ejecting into the float valve body 12, the buoyancy of the float valve body 12 is increased and the float valve body 12 is raised in the condensate W in the valve chamber 4, and the float valve body 12 is raised by this valve body rise. By allowing the valve seat 11 to be seated and closing the valve port 11a, the outflow of the steam S from the valve chamber 4 through the valve port 11a is prevented.

  Further, when the inflow of the steam S from the inflow passage 8a disappears and the condensate W flows in, the staying steam S in the float valve body 12 flows out from the inside of the float valve body 12 through the steam vent small holes 12b. In addition, as the staying steam S in the float valve body 12 condenses into the condensate W, the condensate W in the valve chamber 4 enters the float valve body 12 through the lower opening 12a. The valve body 12 is lowered in the condensate W in the valve chamber 4, and the float valve body 12 is separated from the valve seat 11 by opening the valve body 11 to open the valve port 11a. W is discharged from the valve chamber 4 through the valve port 11a.

  That is, in the float type steam trap having such a structure, the valve body abutment of the valve seat 11 is made of a metal having a natural potential higher than that of the metal forming the float valve body 12 as in the steam trap shown in the above-described embodiment. You may make it implement this invention (namely, the above-mentioned 1st-6th characteristic structure) including the formation of a part.

  In the steam trap shown in FIG. 4, the same reference numerals as those used in the above embodiment are attached to the same portions as the steam trap shown in the above embodiment.

  The present invention provides a valve seat in which a valve opening is formed in a valve chamber into which gas and liquid flow in through an inflow passage, and the valve seat is opened to the valve chamber. A float type valve body that opens and closes the valve port is built in the valve chamber, and one of gas and liquid is selectively discharged from the valve chamber through the valve port by opening and closing the valve port by this valve body. If it is a float type valve device, it can be applied not only to a steam trap but also to various valve devices such as an air trap and an air vent.

  In the application of the present invention, the specific structure of the valve seat and the valve body is not limited to the structure shown in the above-described embodiment, and may be any structure, for example, the valve body contact portion of the valve seat and The structure in which the other part of the valve seat is integrally formed of the same metal, or the valve body is only allowed to rotate around the specific rotation axis while the valve body is suspended in the liquid, and is seated on the valve seat A structure that moves between a state and a state of separation from the valve seat may be used.

  In practicing the present invention, the metal that forms the valve body and the metal that forms the valve body contact portion of the valve seat (that is, a metal that is precious than the valve body) are specifically selected. Whether or not to do so may be appropriately determined according to functions required for each of the valve body and the valve seat, various conditions, and the like.

Structure of float type steam trap Enlarged perspective view of support seat Table showing the natural potential of various metals Structure diagram of float type steam trap showing another embodiment

Explanation of symbols

8a Inflow path S Gas W Liquid 4 Valve chamber 11a Valve port 11 Valve seat 12 Valve body 11A Valve body abutting portion of valve seat 13a Support seat x Axial axis between support seats p Center axis of valve seat

Claims (5)

In the valve chamber into which gas and liquid flow in through the inflow path, a valve seat is formed that forms a valve opening that opens to the valve chamber.
A float-type valve element that opens and closes the valve port by moving away from the valve seat by moving in a liquid floating state is provided in the valve chamber,
A float type valve device configured to selectively discharge one of gas and liquid from the valve chamber through the valve port by opening and closing the valve port by the valve body,
The float type valve apparatus which formed the valve body contact part of the said valve seat with the noble metal of natural potential rather than the metal which forms the said valve body.   The float type valve device according to claim 1, wherein a difference in natural potential between a metal forming the valve body contact portion of the valve seat and a metal forming the valve body is 0.4 V vs SCE or less.   The float type valve device according to claim 1 or 2, wherein a support seat is provided in the valve chamber for supporting the valve body together with the valve seat in contact with the valve body in a state where the valve body is seated on the valve seat. .   The two support seats are arranged in a state in which the axial line between the two support seats and the central axis of the valve seat are in a torsional positional relationship, and the valve body is formed by the two support seats and the valve seat. The float type valve device according to claim 3, wherein the three-point structure is supported at three points. The valve contact portion of the support seat is formed of a metal having a lower natural potential than the metal forming the valve body, or a metal having a natural potential equal to or substantially equal to the metal forming the valve body. Item 5. The float type valve device according to item 3 or 4.

Images