JP3403003B2

JP3403003B2 - Emergency valve for water tank

Info

Publication number: JP3403003B2
Application number: JP14649697A
Authority: JP
Inventors: 和男戸崎
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 1997-06-04
Filing date: 1997-06-04
Publication date: 2003-05-06
Anticipated expiration: 2017-06-04
Also published as: JPH10332014A

Description

【発明の詳細な説明】【０００１】【発明の属する技術分野】本発明は、水道施設の配水本
管と耐震貯水槽の間の管路に介設して、配水本管の破損
等の異常事態発生時に緊急に作動させ、貯水槽への汚水
の流入を防止するとともに、配水本管の通水を確保する
ように構成されている貯水槽用緊急弁に関する。【０００２】【従来の技術】従来より、たとえば図４に示すような水
道施設における配水本管１の上流側本管１Ａと耐震貯水
槽２（以下、単に貯水槽２という）の入口２Ａとを連通
させる流入管３に介設した流入弁４と、貯水槽２の出口
２Ｂと配水本管１の下流側本管１Ｂとを連通させる流出
管５に介設した流出弁６および流入管３における流入弁
４の上流位置と流出管５における流出弁６の下流位置、
つまり流入管３の一次側３Ａと流出管５の二次側５Ｂと
を連通させるバイパス管７に介設したバイパス弁８の３
個の弁４、６、８を使用した貯水槽用緊急弁が知られて
いる。なお、図中Ｖ１、Ｖ２、Ｖ３は制水弁を示す。【０００３】前記構成の従来の貯水槽用緊急弁におい
て、平常時には、図４のようにバイパス弁８と制水弁Ｖ
１が弁閉され、流入弁４と流出弁６および制水弁Ｖ２、
Ｖ３が弁開される。このため、水は矢印で示すように、
配水本管１の上流側本管１Ａ→流入管３の一次側３Ａ→
流入弁４→流入管３の二次側３Ｂの経路で貯水槽２に流
入して貯水される。また、貯水槽２から出た水は、流出
管５の一次側５Ａ→流出弁６→流出管５の二次側５Ｂ→
配水本管１の下流側本管１Ｂの経路で流下する。この状
態で貯水槽２は水道管路の一部として機能する。【０００４】一方、たとえば、地震などにより配水本管
１に破損等の異常事態が発生して、配水本管１の水圧が
設定値以下に低下すると、この水圧を検知して、図５に
示すように、流入弁４と流出弁６が弁閉され、バイパス
弁８が弁開する。このため、水は矢印で示すように、配
水本管１の上流側本管１Ａ→流入管３の一次側３Ａ→バ
イパス管７→流出管５の二次側５Ｂ→配水本管１の下流
側本管１Ｂの経路で流下する。これにより、貯水槽２へ
の汚水の流入を防止して、応急給水用の飲料水を貯水槽
２内に確保するとともに、配水本管１の通水確保により
配水本管１に接続されている消火栓（図示省略）などの
使用可能な状態を得ることができる。【０００５】しかし、前記従来の貯水槽用緊急弁は、流
入弁４と流出弁６およびバイパス弁８の３つの弁を必要
とし弁の使用台数が多くなり、それだけ誤動作が生じる
確率も高くなる。このため、異常事態の発生時に、前記
３つの弁の少なくとも１つの弁に誤動作が生じると、貯
水槽２への汚水の流入を防止できても配水本管１の通水
が確保されない不都合、あるいは、配水本管１の通水を
確保できても貯水槽２への汚水の流入を防止できない不
都合などが発生する。しかも、大きい設置スペースが必
要になる。【０００６】そこで、弁の使用台数を減らし、弁の誤動
作が生じる確率を低くすることで、前述の欠点を解消し
た貯水槽用緊急弁が提案されている。この種の貯水槽用
緊急弁は、図６および図７に示すように、１台の緊急遮
断式のバタフライ弁９を備えている。バタフライ弁９
は、配水本管１側の分流管１０Ａと、貯水槽２側の分流
管１０Ｂとの間に介設される。配水本管１側の分流管１
０ＡはＴ字管１１を介して流入管３の一次側３Ａと流出
管５の二次側５Ｂに接続され、貯水槽２側の分流管１０
ＢはＴ字管１２を介して流入管３の二次側３Ｂと流出管
５の一次側５Ａに接続される。また、配水本管１側の分
流管１０Ａは、上側の通路５Ｂ１と下側の通路３Ａ１に
区画されており、貯水槽２側の分流管１０Ｂは、上側の
通路５Ａ１と下側の通路３Ｂ１に区画されている。そし
て、Ｔ字管１１には、流入管３の一次側３Ａと配水本管
１側の分流管１０Ａにおける下側の通路３Ａ１とを連通
させ、かつ流出管５の二次側５Ｂと配水本管１側の分流
管１０Ａにおける上側の通路５Ｂ１とを連通させる隔壁
１１Ａが設けられ、Ｔ字管１２には、流入管３の二次側
３Ｂと貯水槽２側の分流管１０Ｂにおける下側の通路３
Ｂ１とを連通させ、かつ流出管５の一次側５Ａと配水本
管１側の分流管１０Ｂにおける上側の通路５Ａ１とを連
通させる隔壁１２Ａが設けられている。なお、図６中Ｖ
１は制水弁を示す。【０００７】このような構成であれば、平常時には、図
６および図７のようにバタフライ弁９が弁開され、制水
弁Ｖ１が弁閉される。このため、水は矢印で示すよう
に、配水本管１の上流側本管１Ａ→流入管３の一次側３
Ａ→Ｔ字管１１→配水本管１側の分流管１０Ａの下側の
通路３Ａ１→バタフライ弁９→貯水槽２側の分流管１０
Ｂの下側の通路３Ｂ１→流入管３の二次側３Ｂの経路で
貯水槽２に流入して貯水される。また、貯水槽２から出
た水は、流出管５の一次側５Ａ→Ｔ字管１２→貯水槽２
側の分流管１０Ｂの上側の通路５Ａ１→バタフライ弁９
→配水本管１側の分流管１０Ａの上側の通路５Ｂ１→Ｔ
字管１１→流出管５の二次側５Ｂ→配水本管１の下流側
本管１Ｂの経路で流下する。この状態で貯水槽２は水道
管路の一部として機能する。【０００８】一方、たとえば、地震などにより配水本管
１に破損等の異常事態が発生して、配水本管１の水圧が
設定値以下に低下すると、この水圧を検知して、図８お
よび図９に示すようにバタフライ弁９が弁閉する。この
ため、水は矢印で示すように、配水本管１の上流側本管
１Ａ→流入管３の一次側３Ａ→Ｔ字管１１→配水本管１
側の分流管１０Ａの下側の通路３Ａ１→バタフライ弁９
の手前→配水本管１側の分流管１０Ａの上側の通路５Ｂ
１→Ｔ字管１１→流出管５の二次側５Ｂ→配水本管１の
下流側本管１Ｂの経路で流下する。これにより、貯水槽
２への汚水の流入を防止して、応急給水用の飲料水を貯
水槽２内に確保するとともに、配水本管１の通水確保に
より配水本管１に接続されている消火栓（図示省略）な
どの使用可能な状態を得ることができる。【０００９】しかし、弁の使用台数を減らすように工夫
された上記の貯水槽用緊急弁は、上側の通路５Ｂ１と下
側の通路３Ａ１に区画した配水本管１側の分流管１０Ａ
と、上側の通路５Ａ１と下側の通路３Ｂ１に区画した貯
水槽２側の分流管１０Ｂと、流入管３の一次側３Ａと配
水本管１側の分流管１０Ａにおける下側の通路３Ａ１と
を連通させ、かつ流出管５の二次側５Ｂと配水本管１側
の分流管１０Ａにおける上側の通路５Ｂ１とを連通させ
る隔壁１１Ａが設けられたＴ字管１１および流入管３の
二次側３Ｂと貯水槽２側の分流管１０Ｂにおける下側の
通路３Ｂ１とを連通させ、かつ流出管５の一次側５Ａと
貯水槽２側の分流管１０Ｂにおける上側の通路５Ａ１と
を連通させる隔壁１２Ａが設けられたＴ字管１２を必要
とする。しかも、これら配水本管１側の分流管１０Ａ、
貯水槽２側の分流管１０Ｂ、Ｔ字管１１およびＴ字管１
２は、それぞれ構造が複雑であるから製作が困難であ
る。【００１０】そこで、本発明出願人は、特願平９−１１
３７２号において、弁の使用台数を減らし、異常事態の
発生時に前述の不都合が発生する確率を低下させること
で信頼性を高めるとともに、設置スペースを縮小し、か
つ構造が複雑な分流管やＴ字管などの配管材料の使用を
省略して、簡単に製作することができる貯水槽用緊急弁
を既に提案している。ところが、この貯水槽用緊急弁が
平常時において弁開され、異常事態の発生時において弁
閉されている状態を容易に確認したい要望がある。【００１１】【発明が解決しようとする課題】すなわち、従来の貯水
槽用緊急弁の欠点を解消すべく本発明出願人が提案して
いる貯水槽用緊急弁では、平常時においては弁本体が弁
箱の軸方向の一方側に移動して弁開され、異常事態の発
生時においては弁本体が弁箱の軸方向の他方側に移動し
て弁閉されるように構成されているものの、このような
貯水槽用緊急弁の全開状態および全閉状態を容易に確認
したい要望に対応できないという問題があった。【００１２】そこで、本発明は、従来の貯水槽用緊急弁
の欠点を解消した貯水槽用緊急弁において、全開状態お
よび全閉状態を簡単な構造で容易に確認することができ
る貯水槽用緊急弁を提供することを目的としたものであ
る。【００１３】【課題を解決するための手段】前記目的を達成するため
に、本発明は、筒状の弁箱の周壁部に配水本管の上流側
本管に通じる第１流入ポートと、配水本管の下流側本管
に通じる第１流出ポートと、貯水槽の入口に通じる第２
流出ポートと、貯水槽の出口に通じる第２流入ポートが
設けられ、前記弁箱の内部に、軸方向に移動自在な弁棒
部と、この弁棒部の軸方向一端部に取付けられたピスト
ン部と、弁棒部の軸方向他端部側に取付けられた第１弁
体部及びピストン部と、弁棒部の軸方向略中央部に取付
けられた第２弁体部とを備えた弁本体が装入されてお
り、また、前記弁箱の内部には、弁箱の軸方向に並べて
それぞれ環状の第１弁箱シート、第２弁箱シート及び第
３弁箱シートが設けられているとともに、弁箱の軸方向
の他端側には弁本体を軸方向一端側に向けて常時付勢す
る付勢手段の付勢力を前記他端ピストン部に負荷する付
勢室が形成され、かつ、弁箱の軸方向の一端側には配水
本管の上流側本管の水圧をパイロット圧として導入し前
記一端ピストン部に負荷させることで弁本体を前記付勢
手段の付勢力に抗して軸方向他端側に移動させる圧力室
が形成されており、配水本管の水圧が設定値を超えてい
る平常時には、前記圧力室に導入されるパイロット圧に
より弁本体を付勢手段の付勢力に抗して前記弁箱の軸方
向の他端側に移動させて前記第２弁体部を第２弁箱シー
トに当接させ、かつ、前記第１弁体部を第３弁箱シート
から離間させることにより、第１弁箱シートと第２弁箱
シート間に形成される流入室を介して前記第１流入ポー
トと第２流出ポートを連通させるとともに、第２弁箱シ
ートと第３弁箱シート間に形成される流出室を介して第
１流出ポートと第２流入ポートを連通させて、前記貯水
槽を配水管路の一部として機能させる一方、配水本管の
水圧が設定値以下に低下した異常事態発生時には、付勢
手段の付勢力により前記弁本体を前記弁箱の軸方向の一
端側に移動させて前記第２弁体部を第１弁箱シートに当
接させ、かつ、前記第１弁体部を第３弁箱シートに当接
させることにより、前記流入室及び流出室を介して前記
第１流入ポートと第１流出ポートを連通させて、前記貯
水槽への汚水の流入を防止して該貯水槽内に飲料水を確
保するとともに、前記配水本管の通水を確保するように
構成した貯水槽用緊急弁であって、前記弁箱の内部に連
通して該弁箱の外側に前記軸方向に延びて取付けられた
筒状の弁棒カバーと、この弁棒カバーの内部に挿入され
た前記弁棒部の弁箱外突出部と、この弁箱外突出部に固
着された弁開度指示部材と、前記軸方向に延びて前記弁
棒カバーの周壁部に貫設された前記弁開度指示部材の目
視用窓部とを具備してなり、弁本体の軸方向移動に伴う
弁開度を指示する開度指示装置が前記弁箱の軸方向の両
端部の少なくともいずれか一方に設けられていることを
特徴としている。【００１４】本発明によれば、平常時においては配水本
管の水圧が圧力室に導入され、それをパイロット圧とし
て弁本体が弁箱の軸方向の他端側に移動して第２弁体部
が第２弁箱シートに当接し、かつ、前記第１弁体部が第
３弁箱シートから離間されるように弁開（全開）され
る。このとき、弁棒部の弁箱外突出部に固着された弁開
度指示部材は、筒状の弁棒カバーの軸方向の一方側に偏
った全開指示位置に在り、この全開指示位置に在る弁開
度指示部材を目視用窓部から視認することによって、弁
本体の全開状態を確認できる。また、異常事態発生時に
おいては付勢手段の付勢力により弁本体が弁箱の軸方向
の一端側に移動して第２弁体部が第１弁箱シートに当接
し、かつ、第１弁体部が第３弁箱シートに当接されるよ
うに弁閉（全閉）される。このとき、弁棒部の弁箱外突
出部に固着された弁開度指示部材は、筒状の弁棒カバー
の軸方向の他方側に偏った全閉指示位置に在り、この全
閉指示位置に在る弁開度指示部材を目視用窓部から視認
することによって、弁本体の全閉状態を確認できる。【００１５】【発明の実施の形態】以下、本発明の一実施の形態を図
面に基づいて説明する。図１は本発明の平常時における
一実施の形態を一部断面にして示す構成図である。な
お、前記従来例と同一もしくは相当部分には同一符号を
付して説明する。図１において、貯水槽用緊急弁Ｖは、
１つの筒状の弁箱１３と、この弁箱１３の内部に軸方向
に移動自在に装入された弁本体１４とを備えている。弁
本体１４は弁棒部１４Ｄと、この弁棒部１４Ｄの軸方向
一端部に取付けられたピストン部１４Ａと、弁棒部１４
Ｄの軸方向の他端側に偏って取付けられた第１弁体部１
４Ｂおよびピストン部１４Ｆと、弁棒部１４Ｄの軸方向
の略中央部に取付けられた第２弁体部１４Ｃを有し、ピ
ストン部１４Ａ、第１弁体部１４Ｂ、第２弁体部１４
Ｃ、ピストン部１４Ａおよびピストン部１４Ｆの外周面
と弁箱１３の内周面とで水封できるように構成されてい
る。【００１６】弁箱１３の内部には、環状の第１弁箱シー
ト１３Ａ、環状の第２弁箱シート１３Ｂおよび環状の第
３弁箱シート１３Ｃが軸方向に並べて設けられ、ピスト
ン部１４Ａは環状の第１弁箱シート１３Ａの軸方向一端
側の圧力室１６内に位置し、ピストン部１４Ｆは軸方向
他端側の付勢室１７内に位置しており、第１弁体部１４
Ｂは付勢室１７の近くに位置している。また、第２弁体
部１４Ｃは環状の第１弁箱シート１３Ａと環状の第２弁
箱シート１３Ｂの間に形成される流入室１８内に位置し
ており、環状の第２弁箱シート１３Ｂと環状の第３弁箱
シート１３Ｃの間に流出室１９が形成されている。【００１７】一方、弁箱１３には、その周壁を貫通して
流入室１８に通じる第１流入ポートＰ１と、流出室１９
に通じる第１流出ポートＰ２が形成されているととも
に、これら各ポートＰ１，Ｐ２の形成位置から周方向に
１８０゜離れた位置の周壁を貫通して、第１弁箱シート
１３Ａを介して流入室１８に通じる第２流出ポートＰ３
と、第３弁箱シート１３Ｃを介して流出室１９に通じる
第２流入ポートＰ４が形成されている。また、前記弁箱
１３の一端部を貫通して圧力室１６に通じるパイロット
ポートＰ５が形成され、前記付勢室１７内にはスプリン
グによってなる付勢手段１５が装入されており、弁本体
１４を軸方向一端側に向けて常時付勢している。【００１８】貯水槽用緊急弁Ｖは、水道施設における配
水本管１と貯水槽２の間に介設される。すなわち、配水
本管１の上流側本管１Ａは流入管３の一次側３Ａを介し
て第１流入ポートＰ１に接続され、配水本管１の下流側
本管１Ｂは流出管５の二次側５Ｂを介して第１流出ポー
トＰ２に接続されるとともに、貯水槽２の入口２Ａは流
入管３の二次側３Ｂを介して第２流出ポートＰ３に接続
され、貯水槽２の出口２Ｂは流出管５の一次側５Ａを介
して第２流入ポートＰ４に接続されている。また、配水
本管１の上流側本管１Ａはパイロット管２０を介してパ
イロットポートＰ５に接続されている。図中Ｖ１は制水
弁を示す。【００１９】他方、付勢室１７の外側には、図１および
図２に示すように、軸方向他端側に延びる弁本体の開度
指示装置３０が設けられている。この弁本体の開度指示
装置３０は、付勢室１７の外端壁部１７Ａに貫設した弁
棒挿通孔１７ａを介して付勢室１７の内部に連通して該
付勢室１７の外側に軸方向他端側に延びて水密に取付け
られた筒状の弁棒カバー３０Ａと、弁棒挿通孔１７ａを
貫通して弁棒カバー３０Ａの内部に挿入された弁棒部の
弁箱外突出部１４ｄと、この弁箱外突出部１４ｄに固着
された扇型もしくは円盤状の弁開度指示部材３０Ｂ（た
だし、本実施の形態では扇型の弁開度指示部材３０Ｂを
固着している）と、弁開度指示部材３０Ｂの外周部に対
応し、かつ前記軸方向に延びて弁棒カバー３０Ａの周壁
部に貫設された弁開度指示部材３０Ｂの目視用窓部３０
Ｃとを具備しており、弁開度指示部材３０Ｂの目視用窓
部３０Ｃ近くの弁棒カバー３０Ａの周壁部には、目視用
窓部３０Ｃの軸方向の他端側（一方側）に偏って文字
「開」が表示され、目視用窓部３０Ｃの軸方向の一端側
（他方側）に偏って文字「閉」が表示されている。【００２０】このような構成であれば、平常時には、配
水本管１の水圧が設定値を超えており、この水圧がパイ
ロット圧としてパイロットポートＰ５から圧力室１６に
導入されて、弁本体１４のピストン部１４Ａに負荷し、
付勢手段１５の付勢に抗して弁本体１４が弁箱１３の軸
方向他端側に移動される。これにより、図１に示すよう
に、流入室１８を介して、第１流入ポートＰ１と第２流
出ポートＰ３が連通するとともに、流出室１９を介し
て、第１流出ポートＰ２と第２流入ポートＰ４が連通す
る。このため、水は矢印で示すように、配水本管１の上
流側本管１Ａ→流入管３の一次側３Ａ→第１流入ポート
Ｐ１→流入室１８→→第２流出ポートＰ３→流入管３の
二次側３Ｂの経路で貯水槽２に流入して貯水される。ま
た、貯水槽２から出た水は、流出管５の一次側５Ａ→第
２流入ポートＰ４→流出室１９→第１流出ポートＰ２→
流出管５の二次側５Ｂ→配水本管１の下流側本管１Ｂの
経路で流下する。この状態で貯水槽２は水道管路の一部
として機能する。【００２１】この場合、弁棒部の弁箱外突出部１４ｄに
固着されている弁開度指示部材３０Ｂは、筒状の弁棒カ
バー３０Ａの軸方向の一方側に偏った全開指示位置、つ
まり表示文字「開」に対応する位置に在り、この全開指
示位置に在る弁開度指示部材３０Ｂを目視用窓部３０Ｃ
から視認することによって、弁本体１４の全開状態を確
認することができる。【００２２】一方、たとえば、地震などにより配水本管
１に破損等の異常事態が発生して、配水本管１の水圧が
設定値以下に低下し、圧力室１６のパイロット圧が低く
なると付勢手段１５の付勢力により、図３に示すように
第２弁体部１４Ｃが第１弁箱シート１３Ａに当接し、か
つ第１弁体部１４Ｂが第３弁箱シート１３Ｃに当接する
位置まで弁本体１４が弁箱１３の軸方向一端側に移動さ
れる。これにより、流入室１８と流出室１９を介して第
１流入ポートＰ１と第１流出ポートＰ２が連通する。こ
のため、水は矢印で示すように、配水本管１の上流側本
管１Ａ→流入管３の一次側３Ａ→第１流入ポートＰ１→
流入室１８→流出室１９→第１流出ポートＰ２→流出管
５の二次側５Ｂ→配水本管１の下流側本管１Ｂの経路で
流下する。したがって、貯水槽２への汚水の流入を防止
して、応急給水用の飲料水を貯水槽２内に確保するとと
もに、配水本管１の通水確保により配水本管１に接続さ
れている消火栓（図示省略）などの使用可能な状態を得
ることができる。【００２３】この場合、弁棒部の弁箱外突出部１４ｄに
固着されている弁開度指示部材３０Ｂは、筒状の弁棒カ
バー３０Ａの軸方向の他方側に偏った全閉指示位置、つ
まり表示文字「閉」に対応する位置に在り、この全閉指
示位置に在る弁開度指示部材３０Ｂを目視用窓部３０Ｃ
から視認することによって、弁本体１４の全閉状態を確
認することができる。【００２４】なお、前記実施の形態では、開度指示装置
３０を付勢室１７の外側に設けているが、この付勢室１
７の外側に設けられている開度指示装置３０に代えて、
圧力室１６の外側に開度指示装置３０を設けてもよい。
また、付勢室１７の外側と圧力室１６の外側のそれぞれ
に開度指示装置３０を設けた構成であってもよい。【００２５】【発明の効果】以上説明したように、本発明は、平常時
において弁開され、異常事態の発生時において弁閉され
ている状態を容易に確認したい要望を満足させることが
できるとともに、電気的な開度指示装置などと比較し
て、構造が簡単で経済的にも有利であり、かつ開度指示
弁の信頼性を高めることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality such as breakage of a water distribution main pipe which is provided in a pipe between a water distribution main pipe of a water supply facility and an earthquake-resistant water storage tank. Emergency operation when a situation occurs, preventing inflow of sewage into the water storage tank and securing water flow through the distribution mains
The present invention relates to a water tank emergency valve configured as described above . 2. Description of the Related Art Conventionally, an upstream main pipe 1A of a water distribution main pipe 1 and an inlet 2A of an earthquake-resistant water storage tank 2 (hereinafter simply referred to as a water storage tank 2) in a water supply facility as shown in FIG. The inflow valve 4 provided in the inflow pipe 3 to communicate with the outflow valve 6 and the inflow pipe 3 provided in the outflow pipe 5 for communicating the outlet 2B of the water storage tank 2 with the downstream main pipe 1B of the water distribution main pipe 1. An upstream position of the inflow valve 4 and a downstream position of the outflow valve 6 in the outflow pipe 5,
That third inlet pipe 3 on the primary side 3A and the flow extraction tube 5 of the secondary side 5B and the bypass valve 8 is interposed in the bypass pipe 7 for communicating
An emergency valve for a water tank using a plurality of valves 4, 6, 8 is known. In the drawings, V1, V2, and V3 indicate water control valves. In the conventional emergency valve for a water storage tank having the above-described structure, the bypass valve 8 and the water control valve V are normally used as shown in FIG.
1 is closed, the inflow valve 4 and the outflow valve 6 and the water control valve V 2 ,
V3 is opened. For this reason, the water is
Main pipe 1A upstream of water distribution main pipe 1 → primary side 3A of inflow pipe 3 →
The inflow valve 4 → flows into the water storage tank 2 on the secondary side 3B of the inflow pipe 3 and is stored. Further, the water that has flowed out of the water storage tank 2 is discharged from the primary side 5A of the outflow pipe 5 → the outflow valve 6 → the secondary side 5B of the outflow pipe 5 →
It flows down the route of the main pipe 1B downstream of the water distribution main pipe 1. In this state, the water storage tank 2 functions as a part of the water pipe. On the other hand , for example, when an abnormal situation such as breakage occurs in the water distribution main 1 due to an earthquake or the like and the water pressure of the water distribution main 1 drops below a set value, the water pressure is detected and shown in FIG. Thus, the inflow valve 4 and the outflow valve 6 are closed, and the bypass valve 8 is opened. Therefore, as shown by the arrow, the water flows upstream as shown by the arrow 1A of the main distribution pipe 1 → primary 3A of the inflow pipe 3 → bypass pipe 7 → secondary side 5B of the discharge pipe 5 → downstream of the distribution main pipe 1. It flows down along the path of the main pipe 1B. Thereby, the inflow of sewage into the water storage tank 2 is prevented, drinking water for emergency water supply is secured in the water storage tank 2, and the water supply main pipe 1 is connected to the water distribution main pipe 1 by securing water flow. A usable state such as a fire hydrant (not shown) can be obtained. However, the conventional emergency valve for a water storage tank requires three valves, ie, an inflow valve 4, an outflow valve 6, and a bypass valve 8, and the number of used valves increases, which increases the probability of malfunction. For this reason, if at least one of the three valves malfunctions when an abnormal situation occurs, the inflow of the water distribution main pipe 1 is not ensured even if the inflow of sewage into the water storage tank 2 can be prevented, or However, even if the water distribution of the water distribution main pipe 1 can be ensured, inconvenience that the inflow of sewage into the water storage tank 2 cannot be prevented occurs. In addition, a large installation space is required. [0006] Therefore, reducing the number used in the valve, by lowering the probability of malfunction of the valve occurs, water tank for emergency valve which overcomes the aforementioned drawbacks have been proposed. As shown in FIGS. 6 and 7, this type of emergency valve for a water storage tank includes one emergency shutoff type butterfly valve 9. Butterfly valve 9
Is provided between the distribution pipe 10A on the water distribution main pipe 1 side and the distribution pipe 10B on the water storage tank 2 side. Dividing pipe 1 on the water distribution main pipe 1 side
0A is connected to the primary side 3A of the inflow pipe 3 and the secondary side 5B of the outflow pipe 5 through the T-shaped pipe 11, and is connected to the branch pipe 10 of the water storage tank 2 side.
B is connected to a secondary side 3B of the inflow pipe 3 and a primary side 5A of the outflow pipe 5 via a T-shaped pipe 12. The distribution pipe 10A on the water distribution main pipe 1 side is partitioned into an upper passage 5B1 and a lower passage 3A1, and the distribution pipe 10B on the water storage tank 2 side is divided into an upper passage 5A1 and a lower passage 3B1. It is partitioned. The T-tube 11 has a primary side 3A of the inflow pipe 3 and a water distribution main pipe.
A partition wall 11A is provided to communicate the lower passage 3A1 in the first branch pipe 10A and to communicate the secondary side 5B of the outflow pipe 5 and the upper passage 5B1 in the water distribution main pipe 1 side branch pipe 10A. , The T-shaped pipe 12, the lower passage 3 in the secondary side 3 </ b > B of the inflow pipe 3 and the branch pipe 10 </ b > B in the water storage tank 2 side.
Communicated, and partition wall 1 2 A for communicating the upper passage 5A1 at the primary side 5A and water distribution mains 1 side of the distribution pipe 10B of the outflow pipe 5 is provided and B1. In FIG. 6 V
Reference numeral 1 denotes a water control valve. With such a configuration, in normal times, the butterfly valve 9 is opened and the water control valve V1 is closed as shown in FIGS. Therefore, as shown by the arrow, the water flows from the upstream main pipe 1A of the water distribution main pipe 1 to the primary side 3 of the inflow pipe 3.
A → T-shaped pipe 11 → Lower passage 3A1 on distribution pipe 10A on water distribution main pipe 1 side → Butterfly valve 9 → Distribution pipe 10 on water storage tank 2 side
B flows into the water storage tank 2 via the lower passage 3B1 → the secondary side 3B of the inflow pipe 3 and is stored therein. The water that has flowed out of the water storage tank 2 is discharged from the primary side 5A of the outflow pipe 5 → the T-shaped pipe 12 → the water storage tank 2
Passage 5A1 on the upper side of the side branch pipe 10B → butterfly valve 9
→ The upper passage 5B1 of the distribution pipe 10A on the water distribution main pipe 1 side → T
It flows down along the path of the pipe 11 → the secondary side 5B of the outflow pipe 5 → the downstream main pipe 1B of the water distribution main pipe 1. In this state, the water storage tank 2 functions as a part of the water pipe. On the other hand , for example, when an abnormal situation such as breakage occurs in the water distribution main 1 due to an earthquake or the like and the water pressure of the water distribution main 1 drops below a set value, the water pressure is detected, and FIG. As shown in FIG. 9, the butterfly valve 9 closes. For this reason, as shown by an arrow, water flows from the upstream main pipe 1A of the water distribution main pipe 1 → the primary side 3A of the inflow pipe 3 → the T-shaped pipe 11 → the water distribution main pipe 1
Lower passage 3A1 → Butterfly valve 9
Before → The upper passage 5B of the distribution pipe 10A on the water distribution main pipe 1 side
1 → T-shaped pipe 11 → Secondary side 5B of outflow pipe 5 → Downstream of main pipe 1B downstream of water distribution main pipe 1. Thereby, the inflow of sewage into the water storage tank 2 is prevented, drinking water for emergency water supply is secured in the water storage tank 2, and the water supply main pipe 1 is connected to the water distribution main pipe 1 by securing water flow. A usable state such as a fire hydrant (not shown) can be obtained. [0009] However, the above-mentioned emergency valve for a water storage tank designed to reduce the number of valves used is provided with a branch pipe 10A on the side of the water distribution main pipe 1 divided into an upper passage 5B1 and a lower passage 3A1.
And the lower passage 3A1 in the water distribution tank 2 side divided into the upper passage 5A1 and the lower passage 3B1, the primary side 3A of the inflow pipe 3 and the distribution pipe 10A in the water distribution main pipe 1 side. A T-shaped pipe 11 provided with a partition wall 11A and a secondary side 3B of the inflow pipe 3 are provided to allow communication between the secondary side 5B of the outflow pipe 5 and the upper passage 5B1 of the distribution pipe 10A on the water distribution main pipe 1 side. A partition wall 12A is provided for communicating the flow path with the lower passage 3B1 of the distribution pipe 10B on the water tank 2 side, and for communicating the primary side 5A of the outflow pipe 5 with the upper passage 5A1 of the distribution pipe 10B on the water tank 2 side. Required T-tube 12. In addition, the branch pipe 10A on the side of the water distribution main pipe 1 ,
Dividing pipe 10B, T-shaped pipe 11 and T-shaped pipe 1 on water tank 2 side
2 has a complicated structure, and is therefore difficult to manufacture. Therefore, the applicant of the present invention has filed Japanese Patent Application No. 9-11 / 1997.
In 372, the number of valves used was reduced, and the probability of the above-mentioned inconvenience occurring in the event of an abnormal situation was reduced, thereby increasing reliability, reducing installation space, and using a complicated structure such as a diversion pipe or T-shaped pipe. by omitting the use of piping materials such as tubes, already proposed a reservoir for the emergency valve which can be easily manufactured. However, there is a demand for easily confirming that the emergency valve for a water storage tank is normally opened and closed when an abnormal situation occurs. That is, the applicant of the present invention proposed to solve the drawbacks of the conventional water tank emergency valve.
The reservoir for the emergency valve while creating, in the normal state is a valve to open and move to one side in the axial direction of the valve body the valve casing, the other side in the axial direction of the valve body the valve casing in the event of an abnormal situation navigate although that is configured to so that is closed valves, there is a problem that can not correspond to the demands to be such sure fully open and fully closed reservoir for emergency valve easily. Accordingly, the present invention is directed to a water tank emergency valve which solves the drawbacks of the conventional water tank emergency valve. The water tank emergency valve which can easily confirm the fully opened state and the fully closed state with a simple structure. It is intended to provide a valve. [0013] In order to achieve the above object, the present invention provides a water supply system, comprising: a first inlet port communicating with an upstream main pipe of a water distribution main pipe on a peripheral wall of a cylindrical valve box; A first outlet port leading to the main pipe downstream of the main pipe, and a second outlet port leading to the inlet of the reservoir.
And outlet port, a second inlet port is provided in communication with the outlet of the reservoir, the interior of the valve body, and freely stem portion moves axially attached to one axial end portion of the valve stem portion piste
And a first valve attached to the other end of the valve stem in the axial direction.
Attached to the body, piston, and axial center of valve stem
And a valve main body having a second valve body portion which is provided with a valve body. The valve body is arranged inside the valve box in the axial direction of the valve box.
The first valve box sheet, the second valve box sheet and the second
Three valve box seats are provided and the axial direction of the valve box
The valve body is always urged toward the other end of the
To apply the urging force of the urging means to the piston at the other end.
A power chamber is formed, and water is distributed to one end of the valve box in the axial direction.
Before introducing the water pressure of the main pipe upstream of the main pipe as pilot pressure
The valve body is urged by applying a load to the piston at one end.
Pressure chamber for moving to the other axial side against the urging force of the means
Is formed, and the water pressure in the distribution mains exceeds the set value.
In normal times, the pilot pressure introduced into the pressure chamber is
More valve body second valve box Sea the second valve body portion is moved to the other end side in the axial direction of the valve case against the urging force of the urging means
A first valve body portion and a third valve box sheet.
From the first valve box sheet and the second valve box
Together thereby communicating the first inlet port and the second outlet port through the inlet chamber formed between the sheets, the second Benbakoshi
The first outflow port and the second inflow port communicate with each other through an outflow chamber formed between the port and the third valve box sheet to allow the water storage tank to function as a part of a water distribution pipeline, while the water distribution main pipe is provided. of
At the time of reduced occurrence of the abnormal state that the water pressure is below the set value, the biasing
The valve body is moved to one axial end of the valve box by the urging force of the means, and the second valve body is brought into contact with the first valve box sheet.
And the first valve body is in contact with a third valve box sheet.
By, said through an inlet chamber and an outlet chamber communicated with the first inlet port and the first outlet port to ensure drinking water該貯water tank to prevent the inflow of sewage into the reservoir A water tank emergency valve configured to ensure water flow through the water distribution main pipe , wherein the cylinder communicates with the inside of the valve box and extends in the axial direction and is attached to the outside of the valve box. A valve stem cover, a protruding portion outside the valve box of the valve stem portion inserted into the inside of the valve stem cover, a valve opening degree indicating member fixed to the protruding portion outside the valve case, A visual window of the valve opening indicating member extending through the peripheral wall of the valve stem cover, and accompanying the axial movement of the valve body.
An opening indicating device for indicating a valve opening is provided on at least one of both axial ends of the valve box. According to the present invention, the water distribution book is normally used.
The water pressure of the pipe is introduced into the pressure chamber, which is used as pilot pressure.
The valve body moves to the other axial end of the valve box and the second valve body
Is in contact with the second valve box sheet, and the first valve body is
The valve is opened (fully opened) so as to be separated from the three valve box sheets . At this time, the valve body outside secured to the projecting portion a valve opening degree instruction member of the valve stem portion, Ri standing in the full open instruction position biased to one side in the axial direction of the cylindrical valve stem cover, this fully open instruction position The fully open state of the valve body can be confirmed by visually recognizing the existing valve opening degree indicating member from the visual window. When an abnormal situation occurs, the urging force of the urging means moves the valve body to one axial end of the valve box, and the second valve body contacts the first valve box sheet.
And the first valve body is brought into contact with the third valve box sheet.
Is sea urchin valve closed (fully closed). At this time, stem portion of the valve casing outside the protruding portion fixed to the valve opening instruction member, Ri standing fully closed indication position biased toward the other side in the axial direction of the cylindrical valve rod cover, the full closing command The fully closed state of the valve body can be confirmed by visually recognizing the valve opening degree indicating member at the position from the visual window. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a partial cross section of one embodiment of the present invention in a normal state. The same or corresponding parts as those of the conventional example are denoted by the same reference numerals and described. In FIG. 1, the emergency valve V for a water tank is
One cylindrical valve box 13 and an axial direction inside the valve box 13
And a valve body 14 movably mounted in the valve body 14. The valve body 14 includes a valve stem 14D, a piston 14A attached to one axial end of the valve stem 14D, and a valve stem 14D.
The first valve body portion 1 eccentrically attached to the other end side in the axial direction of D
4B, a piston portion 14F, and a second valve body portion 14C attached to a substantially central portion of the valve stem portion 14D in the axial direction, and includes a piston portion 14A, a first valve body portion 14B, and a second valve body portion 14.
C, the outer peripheral surface of the piston portion 14A and the outer peripheral surface of the piston portion 14F and the inner peripheral surface of the valve box 13 can be water-sealed. Inside the valve box 13, an annular first valve box sheet 13A, an annular second valve box sheet 13B, and an annular third valve box sheet 13C are provided side by side in the axial direction, and the piston portion 14A has an annular shape. Of the first valve box sheet 13A is located in the pressure chamber 16 at one end in the axial direction, and the piston portion 14F is located in the biasing chamber 17 at the other end in the axial direction.
B is located near the urging chamber 17. The second valve body portion 14C is located in the inflow chamber 18 formed between the annular first valve box sheet 13A and the annular second valve box sheet 13B.
Te Contact is, outflow chamber 19 between the annular second valve body sheet 13B and an annular third valve body seat 13C is formed. On the other hand, the valve box 13 has a first inflow port P1 penetrating the peripheral wall thereof and leading to the inflow chamber 18;
A first outflow port P2 is formed, which penetrates the peripheral wall at a position 180 ° in the circumferential direction from the position where these ports P1 and P2 are formed, and flows into the inflow chamber via the first valve box sheet 13A. Second outflow port P3 leading to 18
And a second inflow port P4 communicating with the outflow chamber 19 via the third valve box sheet 13C. Further, a pilot port P5 is formed through one end of the valve box 13 and communicates with the pressure chamber 16. A biasing means 15 made of a spring is inserted in the biasing chamber 17, and a valve body 14 is provided. Is constantly biased toward one end in the axial direction. The water tank emergency valve V is provided between the water distribution main pipe 1 and the water tank 2 in the water supply facility. That is, the upstream main pipe 1A of the water distribution main pipe 1 is connected to the first inflow port P1 via the primary side 3A of the inflow pipe 3, and the downstream main pipe 1B of the water distribution main pipe 1 is connected to the secondary side of the outflow pipe 5. 5B, the inlet 2A of the water storage tank 2 is connected to the second outlet port P3 via the secondary side 3B of the inflow pipe 3, and the outlet 2B of the water storage tank 2 is connected to the outlet 2B. The pipe 5 is connected to the second inflow port P4 via the primary side 5A. An upstream main pipe 1A of the water distribution main pipe 1 is connected to a pilot port P5 via a pilot pipe 20. In the figure, V1 indicates a water control valve. On the other hand, outside the urging chamber 17, as shown in FIGS. 1 and 2, an opening indicating device 30 for a valve body extending toward the other end in the axial direction is provided. The opening degree indicating device 30 of the valve body communicates with the inside of the biasing chamber 17 through a valve rod insertion hole 17 a penetrating through the outer end wall portion 17 </ b> A of the biasing chamber 17, and the outside of the biasing chamber 17. A cylindrical valve stem cover 30A extending toward the other end in the axial direction and attached in a watertight manner, and a valve stem portion inserted through the stem insertion hole 17a into the interior of the stem cover 30A and protrudes outside the valve box. A portion 14d and a fan-shaped or disk-shaped valve opening indicating member 30B fixed to the valve box outer projecting portion 14d (however, in the present embodiment, the fan-shaped valve opening indicating member 30B is fixed). The visual window 30 of the valve opening indicating member 30B corresponding to the outer peripheral portion of the valve opening indicating member 30B and extending in the axial direction and penetrating the peripheral wall of the valve stem cover 30A.
C, the peripheral wall of the valve stem cover 30A near the viewing window 30C of the valve opening indicating member 30B is biased toward the other end (one side) in the axial direction of the viewing window 30C. Thus, the character "open" is displayed, and the character "closed" is displayed on one side (the other side) in the axial direction of the viewing window 30C. With such a configuration, in normal times, the water pressure of the water distribution main pipe 1 exceeds the set value, and this water pressure is introduced into the pressure chamber 16 from the pilot port P5 as the pilot pressure. , Load on the piston portion 14A of the valve body 14,
The valve body 14 against the bias of the biasing means 15 is Ru is moved in the axial direction other end side of the valve body 13. Thereby, as shown in FIG. 1, the first inflow port P1 and the second outflow port P3 communicate with each other via the inflow chamber 18, and the first outflow port P2 and the second inflow port via the outflow chamber 19. P4 communicates. For this reason, as shown by an arrow, water flows as shown by an arrow in the main pipe 1A on the upstream side of the water distribution main pipe 1 → the primary side 3A of the inflow pipe 3 → the first inflow port P1 → the inflow chamber 18 →→ the second outflow port P3 → the inflow pipe 3 Flows into the water storage tank 2 through the path of the secondary side 3B. Further, the water flowing out of the water storage tank 2 is supplied to the primary side 5A of the outflow pipe 5 → the second inflow port P4 → the outflow chamber 19 → the first outflow port P2 →
It flows down from the secondary side 5B of the outflow pipe 5 to the downstream main pipe 1B of the water distribution main pipe 1. In this state, the water storage tank 2 functions as a part of the water pipe. In this case, the valve opening degree indicating member 30B fixed to the outside protruding portion 14d of the valve stem is located at a fully open instruction position biased to one side in the axial direction of the cylindrical valve stem cover 30A. The valve opening degree indicating member 30B located at the position corresponding to the display character "open" and located at the fully opened instruction position is connected to the visual window 30C.
By visually recognizing from, the fully opened state of the valve body 14 can be confirmed. On the other hand , for example, when an abnormal situation such as breakage occurs in the water distribution main 1 due to an earthquake or the like, the water pressure in the water distribution main 1 drops below a set value, and the pilot pressure in the pressure chamber 16 becomes low, so that the urging is performed. by the biasing force of the means 15, contacts the second valve body portion 14C is first valve body seat 13A as shown in FIG. 3, and the position to which the first valve body portion 14B is brought into contact with the third valve body seat 13C The valve body 14 is moved to one axial end of the valve box 13.
Re that. Thereby, the first inflow port P1 and the first outflow port P2 communicate with each other via the inflow chamber 18 and the outflow chamber 19. For this reason, as shown by the arrow, the water flows from the upstream main pipe 1A of the water distribution main pipe 1 → the primary side 3A of the inflow pipe 3 → the first inflow port P1 →
The water flows down along the route of the inflow chamber 18 → outflow chamber 19 → first outflow port P2 → secondary side 5B of outflow pipe 5 → downstream main pipe 1B of water distribution main pipe 1. Therefore, the inflow of sewage into the water storage tank 2 is prevented, drinking water for emergency water supply is secured in the water storage tank 2, and the fire hydrant connected to the water distribution main pipe 1 by securing the water distribution of the water distribution main pipe 1. A usable state such as (not shown) can be obtained. In this case, the valve opening indicating member 30B fixed to the outside protruding portion 14d of the valve stem is provided with a fully closed indicating position biased to the other axial side of the cylindrical valve stem cover 30A. That is, the valve opening degree indicating member 30B located at the position corresponding to the display character "closed" and located at the fully closed instruction position is connected to the visual window 30C.
The fully closed state of the valve body 14 can be confirmed by visually recognizing the valve body 14. In the above-described embodiment, the opening degree indicating device 30 is provided outside the urging chamber 17.
7, instead of the opening degree indicating device 30 provided outside
The opening indicating device 30 may be provided outside the pressure chamber 16.
Further, the configuration may be such that the opening degree indicating device 30 is provided on each of the outside of the urging chamber 17 and the outside of the pressure chamber 16. As described above, according to the present invention, it is possible to satisfy a demand for easily confirming a state where the valve is normally opened and the valve is closed when an abnormal situation occurs. As compared with an electric opening indicating device, the structure is simple and economically advantageous, and the reliability of the opening indicating valve can be improved.

【図面の簡単な説明】【図１】本発明の平常時における一実施の形態を示す構
成図である。【図２】図１のＡ−Ａ線断面図である。【図３】本発明の異常事態発生時における一実施の形態
を示す構成図である。【図４】従来例の平常時における形態を示す構成図であ
る。【図５】従来例の異常事態発生時における形態を示す構
成図である。【図６】他の従来例の平常時における形態を示す構成図
である。【図７】図６のＢ−Ｂ線拡大断面図である。【図８】他の従来例の異常事態発生時における形態を示
す構成図である。【図９】図８のＣ−Ｃ線拡大断面図である。【符号の説明】１配水本管１Ａ上流側本管１Ｂ下流側本管２耐震貯水槽（貯水槽）２Ａ入口２Ｂ出口１３筒状の弁箱１４弁本体１４Ｄ弁棒部１４ｄ弁棒部の弁箱外突出部３０弁本体の開度指示装置３０Ａ弁棒カバー３０Ｂ弁開度指示部材３０Ｃ弁開度指示部材の目視用窓部Ｐ１第１流入ポートＰ２第１流出ポートＰ３第２流出ポートＰ４第２流入ポートＰ５パイロットポートＶ貯水槽用緊急弁BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of the present invention in a normal state. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a configuration diagram showing one embodiment of the present invention when an abnormal situation occurs. FIG. 4 is a configuration diagram showing a form in a normal state of a conventional example. FIG. 5 is a configuration diagram showing a conventional example when an abnormal situation occurs. FIG. 6 is a configuration diagram illustrating a form in a normal state of another conventional example. FIG. 7 is an enlarged sectional view taken along line BB of FIG. 6; FIG. 8 is a configuration diagram showing a form of another conventional example when an abnormal situation occurs. FIG. 9 is an enlarged sectional view taken along line CC of FIG. 8; [Description of Signs] 1 Water distribution main pipe 1A Upstream main pipe 1B Downstream main pipe 2 Seismic storage tank (reservoir) 2A Inlet 2B Outlet 13 Cylindrical valve box 14 Valve body 14D Valve rod portion 14d Valve at valve rod portion Outer box projection 30 Valve body opening indicating device 30A Valve stem cover 30B Valve opening indicating member 30C Visual window P1 of valve opening indicating member First inflow port P2 First outflow port P3 Second outflow port P4 2 inflow port P5 pilot port V water tank emergency valve

───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.⁷，ＤＢ名) F16K 17/36 - 17/42 F16K 17/06 F16K 11/00 - 11/24 F16K 37/00 ──────────────────────────────────────────────────続き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 17/36-17/42 F16K 17/06 F16K 11/00-11/24 F16K 37/00

Claims

(1) A first inflow port communicating with an upstream main pipe of a water distribution main pipe on a peripheral wall portion of a cylindrical valve box, and a first inflow port communicating with a downstream main pipe of the water distribution main pipe. 1 Outflow port and 2nd leading to water tank entrance
And outlet port, a second inlet port is provided in communication with the outlet of the reservoir, the interior of the valve body, and freely stem portion axially, the
A piston attached to one axial end of the valve stem,
The first valve body and the pin attached to the other end of the rod in the axial direction.
The stone part and the valve stem part
And a valve body having two valve bodies. The valve body is arranged inside the valve box in the axial direction of the valve box.
Annular first valve box sheet, second valve box sheet and third valve, respectively
A box seat is provided, and other
On the end side, always bias the valve body toward one end in the axial direction.
An urging chamber for applying the urging force of the urging means to the other end piston portion
A water distribution main pipe is formed at one axial end of the valve box.
Introduce the water pressure of the upstream main pipe as pilot pressure
By applying a load to the piston part once, the valve body is
A pressure chamber that moves to the other end in the axial direction against the urging force of the step
In normal times when the water pressure in the distribution mains exceeds the set value ,
The valve body is urged by the pilot pressure introduced into the pressure chamber.
The valve body is moved to the other axial end of the valve box against the urging force of the step to bring the second valve body portion into contact with the second valve box sheet.
The first valve body is separated from the third valve box sheet.
With this, a sheet is formed between the first valve box sheet and the second valve box sheet.
The first inflow port and the second outflow port communicate with each other through the inflow chamber , and the second valve box sheet and the third valve box
The first outflow port and the second inflow port communicate with each other through an outflow chamber formed between the ports to allow the water storage tank to function as a part of the water distribution pipeline, while the water pressure of the water distribution main pipe is equal to or lower than a set value. When an abnormal situation occurs, the urging force of the urging means moves the valve body to one axial end of the valve box to move the second valve body to the first position.
A first valve body portion which is brought into contact with a valve box sheet, and
By contacting the box sheet, the inflow chamber and outflow
And communicates the first inlet port and the first outlet port through the chamber, while securing a drinking water該貯water tank to prevent the inflow of sewage into the water tank, water flow of the water distribution mains An emergency valve for a water storage tank configured to ensure the following: a cylindrical valve stem cover that is connected to the inside of the valve box and extends outside the valve box in the axial direction and is attached; A projection outside the valve box of the valve stem inserted into the interior of the rod cover, a valve opening indicating member fixed to the projection outside the valve casing, and a peripheral wall portion of the valve stem cover extending in the axial direction. it comprises a and a viewing window of the pierced by said valve opening instruction member, the axial ends of the opening indicating device for indicating the valve opening caused by the axial movement of the valve body the valve body An emergency valve for a water tank, which is provided in at least one of the sections.