【０００１】
【発明の属する技術分野】
本発明は高圧ガス容器の非水槽式耐圧膨張試験方法に関し、特には正確で実用可能な測定精度を実現するために、被検査容器内に充填する水の中に浮遊する微小な気泡を水に溶解させてパージすることにより、効率が良くて精度の高い非水槽式耐圧膨張試験を行う方法に関するものである。
【０００２】
【従来の技術】
一般に液化石油ガスなどに用いられる高圧ガス容器は、加圧状態における安全性を検査するために、製造時並びに所定の期間が経過するごとに耐圧膨張試験を行なう必要がある。この耐圧膨張試験は次式（１）によって求まる恒久増加率によって判定され、この恒久増加率が法律によって規定される一定の値以下であれば合格とされる。これは、恒久増加率の小さい容器ほどその復元力が大きく、耐圧性に優れているからである。
恒久増加率（％）＝｛恒久増加量（Δｖ）÷全増加量（ΔＶ）｝×１００…（１）
【０００３】
ここで全増加量（ΔＶ）は、加圧前のガス容器の容量をＶ１、加圧後の容量をＶ２とすると、Ｖ２−Ｖ１で表わされるガス容器の膨張による容量増加分であり、恒久増加量（Δｖ）は、ガス容器に対する加圧を解除したときのガス容器の容量をＶ３としたときに、Ｖ３−Ｖ１で表わされる、ガス容器の復元が不完全なことによる容量増加分である。
【０００４】
かかる全増加量（ΔＶ）並びに恒久増加量（Δｖ）を測定する試験装置として水槽式と非水槽式とが知られており、このうちの水槽式耐圧膨張試験装置は、検査すべき高圧ガス容器を閉じられた水槽の水中に設置し、当該高圧ガス容器内に外部から高圧水などを圧入して所定の高圧とし、このときに生ずる高圧ガス容器の膨張によって水槽から排出される水の量を水槽に連通して設けたビュレットにおける水位を検出することによって測定するものである。
【０００５】
しかしながら、このような水槽式耐圧膨張試験装置は、原理的に水槽内に充満させておくべき水の量に対して高圧ガス容器に生ずる膨張によって排出される水の量が相当に少なく、従って全体に対する信号の割合が小さくて測定精度が低い欠点がある。更に水槽式耐圧膨張試験装置では使用する水の量が多いため、環境温度によって生ずる水の膨張・収縮による変動量が大きい。この変動量は検出すべき高圧ガス容器の膨張によって排出される水の量に対する誤差となるが、この誤差の大きさが信号量、即ち検出すべき水の量を超えることも稀ではない。特に水槽が大きい場合にこの欠点が著しい。
【０００６】
一方、非水槽式の耐圧膨張試験は被検査容器に予め水を満たしておき、密閉後プランジャポンプで水を送り込むことで被検査容器内の圧力を上げて耐圧検査を行い、送り込んだ水量を計測して所定の計算式により全増加量を求め、加圧後に加圧前の圧力まで減圧した時にプランジャポンプに戻った水量を計測し、送り込んだ水量との差を恒久増加量として求める方法であり、この非水槽式耐圧膨張試験方法によれば、比較的高い精度を有する測定を短時間で行うことができるが、加圧ポンプの作動時にガス容器に脈動が発生することがあり、水圧が不安定となって測定誤差が生じやすいという課題がある。更に各種配管内に残留するエアによって加圧状態が安定せず、しかも加圧力を検出する圧力スイッチの精度は必ずしも良好であるとはいえない上、各種バルブの開閉駆動用電磁切換弁の作動精度が十分でないことも測定誤差を誘発する原因となっている。
【０００７】
上記に対処して、本願出願人は先に特許第３１４５８８８号により、試験に供する高圧ガス容器を定位置に固定してから検査ヘッドを嵌合固定し、検査ヘッドの他端部に設けたエア抜き注水孔からの注水とエア抜き排水を行った後、サーボモータによって駆動されるプランジャポンプを用いて高圧ガス容器内の圧力を一定値にまで高めてサーボモータの位置を読み取り、所定の時間維持した後に高圧ガス容器内の徐圧を行って高圧ガス容器内の水圧が加圧前の値まで下降した際のサーボモータの位置を読み取り、上記各サーボモータの読み取り位置から高圧ガス容器の全増加量と恒久増加量を求め、演算式に基づいて該高圧ガス容器の恒久増加率を計算する高圧ガス容器の非水槽式耐圧膨張試験方法を提案した。
【０００８】
かかる非水槽式耐圧膨張試験方法によれば、検査すべき高圧ガス容器に検査ヘッドを嵌合固定してから検査ヘッドの他端部に設けたエア抜き注水孔からの注水とエア抜き排水とを行い、プランジャポンプによって高圧ガス容器内の圧力を一定値まで高めてサーボモータの位置を読み取り、そのまま所定の時間維持した後に高圧ガス容器内の徐圧を行って水圧が加圧前の値まで下降した際のサーボモータの位置を読み取ることにより、読み取られたサーボモータの位置から高圧ガス容器の全増加量と恒久増加量を求め、演算式に基づいて恒久増加率を計算することができる。
【０００９】
【発明が解決しようとする課題】
しかしながら、非水槽式耐圧膨張試験において水を被検査容器へ給水する時に、被検査容器内での水の跳ね返りや乱流により気泡が発生し、耐圧検査で加圧時に水と気泡の圧縮率の違いから被検査容器内の残留気泡によって加圧目的で送る水量にばらつきが生じることがあり、正確な全増加量と恒久増加量の値を測定出来ないことがある。その対策として耐圧検査を行う前にエアーパージ工程により気泡を除く手段が考慮されているが、このエアーパージ工程はパージ対象の気泡が水面上に浮き上がる目視可能なものに限定されていたため、水中に浮遊する目視が出来ない程の微小気泡に対する対策がとられておらず、不安定なデータしか得られないという課題がある。特にＬＰＧ容器検査機の測定データの精度に関する基準が存在しないため、高圧ガス保安協会が示した見解である「アセチレンボンベ（内容量４１．７リットル）の恒久増加量データが０．３ｃｃ以下であること」を測定データの有効性の判断基準としているが、従来はこの値を達成できなかったこと、及び測定データの不安定性から耐圧膨張試験方法としての実用化が出来ないのが現状である。
【００１０】
従って被検査容器の全増加量、恒久増加量を測定するための媒体として利用する水を、微小気泡が浮遊する気相と液相が混在する状態から、気相を実用上問題ない程度までパージし、液相のみの状態と等価と考えても良い状態にすることが正確なデータを得る上で肝要である。
【００１１】
そこで本発明はこのような従来の非水槽式耐圧膨張試験方法が有している課題を解消して、被検査容器内の残留気泡によって生じる加圧用の水量のばらつきをなくして正確な全増加量と恒久増加量の測定値が得られ、客観的で高い精度を有する測定を短時間で迅速に行うことができる高圧ガス容器の非水槽式耐圧膨張試験方法を提供することを目的とするものである。
【００１２】
【課題を解決するための手段】
本発明は上記目的を達成するために、試験に供する高圧ガス容器の上部に残留する空気をパージした後、被加圧系内を密閉状態にしてポンプで水を送り込むことにより予備加圧工程を行い、水中に浮遊する微小気泡をパージしてから高圧ガス容器内の圧力を一定値にまで高めて所定の時間維持した際の高圧ガス容器の全増加量と、その後に徐圧を行い、高圧ガス容器内の水圧が加圧前の値にまで下降した際の高圧ガス容器の恒久増加量を求め、演算式に基づいて該高圧ガス容器の恒久増加率を計算するようにした高圧ガス容器の非水槽式耐圧膨張試験方法を基本手段として提供する。上記予備加圧工程は、耐圧検査圧力の９０％近辺で、かつ、９０％以下とする。
【００１３】
具体的には試験に供する高圧ガス容器を定位置に固定してから検査ヘッドを嵌合固定し、検査ヘッドからのエア抜き注水を行った後、被加圧系内を密閉状態にしてポンプで水を送り込むことにより予備加圧工程を行い、水中に浮遊する微小気泡をパージしてからサーボモータによって駆動されるプランジャポンプを用いて高圧ガス容器内の圧力を一定値にまで高めてサーボモータの位置を読み取り、所定の時間維持した後に高圧ガス容器内の徐圧を行って高圧ガス容器内の水圧が加圧前の値まで下降した際のサーボモータの位置を読み取り、上記各サーボモータの読み取り位置から高圧ガス容器の全増加量と恒久増加量を求め、演算式に基づいて該高圧ガス容器の恒久増加率を計算する。また、上記サーボモータの回転数をマイクロコンピュータに伝達して、演算式に基づいて耐圧膨張試験を行う高圧ガス容器の全増加量及び恒久増加率を演算するようにした非水槽式耐圧膨張試験方法を提供する。
【００１４】
かかる非水槽式耐圧膨張試験方法によれば、被検査容器に給水した後、該被検査容器の上部に残留する空気を排水弁に押し出すことでパージし、次に排水弁を閉じてから大気開放弁を開いて給水配管内に残留する空気をパージしてから被加圧系内を密閉状態にし、予備加圧工程としてプランジャポンプで水を送り込むことにより、耐圧検査圧力の９０％近辺で、かつ、９０％以下まで昇圧させることで水中に浮遊する微小気泡が水に溶解し、微小気泡をパージすることができる。この微小気泡のパージ後に被加圧系内からプランジャポンプへ水を戻すことで減圧し、加圧前の圧力まで減圧させて予備加圧工程は終了する。予備加圧工程によって微小気泡量を減少あるいは消滅させることができる。
【００１５】
予備加圧工程の終了後に被加圧系内を密閉状態にしてからプランジャポンプで水を送り込んで昇圧させ、その状態を所定時間保持して全増加量を測定し、測定後に加圧前の圧力まで減圧して被検査容器の体積増加分である恒久増加量の演算を行う。
【００１６】
【発明の実施の形態】
以下図面に基づいて本発明にかかる高圧ガス容器の非水槽式耐圧膨張試験方法の具体的な実施形態を説明する。本発明では上記課題を解決するために、気体の水に対する溶解濃度が圧力によって変化することを利用して、被検査容器の上部と給水配管内に残留する空気を注水によってパージした被検査容器の被加圧系内を密閉状態にして、加圧検査前に予備加圧工程を行うことが特徴となっている。
【００１７】
非水槽式耐圧膨張試験方法の処理工程は、大別して給水工程、検査工程、排水工程、乾燥工程の４工程からなる。図３は被検査容器１への給水部分の概略図であり、２１は給水ヘッド、２２は給水パイプ、２３は給水バルブ、２４は排水パイプ、２５は電極スイッチであり、図４の給水ヘッド２１の詳細図に示したように、給水ヘッド２１の下端部を被検査容器１のネックリング２６に接合し、給水パイプ２２を被検査容器１の底部まで差込んでから給水バルブ２３を開放して給水を行う。
【００１８】
被検査容器１内に水が満たされると給水ヘッド２１の排水口入口２７から排水口出口２８を通って排水パイプ２４内に水が溢出する。溢れ出した水により排水パイプ２４に設置した電極スイッチ２５がオンとなり、被検査容器１内が満水状態になったことが検知されるので、給水バルブ２３を閉じて給水を停止する。給水パイプ２２を引き上げた後、給水ヘッド２１を被検査容器１と分離して給水工程が終了し、被検査容器１を次段の検査工程へ送り出す。
【００１９】
次に被検査容器１の検査工程を説明すると、この検査工程は二つのエアパージ工程と耐圧検査工程との計三つの工程から構成されている。図１はエアパージ工程を示す概要図であり、１は給水工程の終了した被検査容器、２は検査ヘッド、３は通水弁、４は排水弁、５は大気開放弁であって、水を満たした被検査容器１に検査ヘッド２を固定した後、通水弁３と排水弁４を開き、大気開放弁５を閉じてから通水弁３を通して給水６を行う。７はサーボモータ、８はプランジャポンプ、９は圧力センサである。
【００２０】
図２により拡大して示す検査ヘッド２から被検査容器１のネックリング２６の下方に突出する注水口１０から被検査容器１へ給水し、被検査容器１の上部に残留する空気を排水口１１から前記排水弁４に押し出すことでパージし、次に図１に示す排水弁４を閉じてから大気開放弁５を開いて給水配管内に残留する空気をパージした後、通水弁３と大気開放弁５を閉じてエアーパージ工程を終了する。
【００２１】
次に本発明の特徴的工程である予備加圧工程に移行する。先ず図１に示した状態から通水弁３、排水弁４、大気開放弁５を閉じて被加圧系内を密閉状態にする。そして密閉された被加圧系内へプランジャポンプ８で水を送り込むことにより、耐圧検査圧力の９０％近辺で、かつ、９０％以下まで昇圧する。約５秒程度その状態を保ちつつ水に圧力を加えることで、水中に浮遊する微小気泡が水に溶解し、微小気泡をパージすることができる。微小気泡のパージ後に被加圧系内からプランジャポンプ８へ水を戻すことで減圧し、加圧前の圧力まで減圧させて予備加圧工程は終了する。
【００２２】
比較的水に溶けにくいガスは（２）式で表されるヘンリーの法則が成立する。
ｐ＝ＨＣ ………（２）
ここでｐは気相中の溶質ガス分圧、Ｃは液濃度、Ｈはヘンリー定数を表わしている。
【００２３】
従って大気圧で気相と液相が平衡状態にあっても、加圧することによって平衡濃度が増加するため、新たな平衡点に向かってガスの溶解がはじまる。このガスを水中に浮遊する微小気泡に置き換えて考えると、加圧することによって微小気泡量を減少あるいは消滅させることができる。
【００２４】
予備加圧工程の終了後に耐圧検査工程を行う。この耐圧検査工程は通水弁３、排水弁４、大気開放弁５を閉じて被加圧系内を密閉状態にし、この密閉された被加圧系内へプランジャポンプ８で水を送り込むことにより、耐圧検査圧の３ＭＰａまで昇圧させて３０秒間加圧する。圧力を３０秒間かけた後に全増加量を測定し、測定後に加圧前の圧力まで減圧して被検査容器１の体積増加分である恒久増加量の演算を行い、耐圧検査工程を終了する。
【００２５】
耐圧膨張試験の具体的方法を簡単に説明すると、被検査容器１を定位置に固定してから検査ヘッド２を嵌合固定し、前記したように該検査ヘッド２からのエア抜き注水を行った後、被加圧系内を密閉状態にして水を送り込むことにより予備加圧工程を行い、水中に浮遊する微小気泡をパージしてからサーボモータ７によって駆動されるプランジャポンプ８を用いて被検査容器１内の圧力を一定値にまで高めてサーボモータ７の位置を読み取り、所定の時間維持した後に被検査容器１内の徐圧を行って水圧が加圧前の値まで下降した際のサーボモータ７の位置を読み取り、上記各サーボモータ７の読み取り位置から被検査容器１の全増加量（ΔＶ）と恒久増加量（Δｖ）を求め、演算式に基づいて該高圧ガス容器の恒久増加率（％）を計算する。
【００２６】
更にサーボモータ７の回転数を図外のマイクロコンピュータに伝達して、演算式に基づいて被検査容器１の全増加量（ΔＶ）と恒久増加量（Δｖ）を求め、被検査容器１の恒久増加率（％）を求めることもできる。
【００２７】
次に排水工程として、被検査容器１のネックリング２６から圧縮空気を送り込み、耐圧検査に使用した水を被検査容器１の底部に達している給水パイプ２２を利用して排水し、次段の乾燥工程に移行する。乾燥工程は加熱乾燥工程と空気置換工程とからなり、加熱乾燥工程はスチームにより被検査容器１の濡れた壁面及び底部に残った水を加熱により乾燥させる工程であり、空気置換工程は加熱乾燥工程終了後に乾燥した圧縮空気を送り込むことで被検査容器１内に残っているスチームと置換する工程である。
【００２８】
ここで本発明の特徴的工程である予備加圧工程について説明すると、図５は縦軸に検査圧力（ＭＰａ）を、横軸に検査時間（ｓｅｃ）を取った加圧パターン図であり、先ず被検査容器１を予備加圧工程１２により約２．５ＭＰａで時間ａだけ予備加圧して水中に浮遊する微小気泡を減少させから耐圧試験工程１３で約３ＭＰａで時間ｂの加圧を行うことで、演算によりΔＶ（全増加量）とΔｖ（恒久増加量）の測定値を得る。時間ａは約５秒，時間ｂは３０秒以上である。上記予備加圧工程１２を実施することで微小気泡の影響を十分無視できる状態にしてから耐圧試験工程１３を行うことが本発明の特徴となっている。
【００２９】
予備加圧工程１２の減圧時１２ａでは溶解した気体が再気化するが、新たな平衡点に達するのに時間がかかるため、予備加圧工程１２の加圧パターンを適切に調整することによって微小気泡の影響を実用上から問題のない程度まで下げることができる。
【００３０】
図６は予備加圧工程１２の有無によるアセチレンボンベの恒久増加量を比較して示すグラフであり、縦軸に恒久増加量（ｃｃ）を、横軸に同一アセチレンボンベの検査回数を取ってある。グラフ１４は予備加圧工程１２がない場合、グラフ１５は予備加圧工程１２を実施した場合の恒久増加量の測定値を表わしている。尚、予備加圧工程１２の条件は圧力２．５ＭＰａで５秒とした。
【００３１】
図６によれば予備加圧工程１２を実施することで恒久増加量（ｃｃ）の測定データが０．３ｃｃ以下になったこと、及び測定データのばらつきが減少して安定したデータが得られるようになったことが分かり、非水槽式耐圧膨張試験の実用化に貢献することができる。
【００３２】
上記により本発明にかかる高圧ガス容器の非水槽式耐圧膨張試験方法を確立することができる。この試験方法は水槽を必要とせず、加圧時に送り込む水量を測定することで被検査容器１の体積増加分を、更に減圧時に被検査容器１から戻す水量を測定することで体積減少分を求めて演算により恒久増加率（％）を測定することができる。非水槽式耐圧膨張試験は水槽がないので構成自体が小型化されるとともに製造コストは低廉となって維持，管理の手間が減少するという特長を有している。
【００３３】
【発明の効果】
以上詳細に説明したように、本発明にかかる高圧ガス容器の非水槽式耐圧膨張試験方法によれば、被検査容器に給水した後に該被検査容器の上部と給水配管内に残留する空気をパージしてから被加圧系内を密閉状態にして予備加圧工程を実施することで水中に浮遊する微小気泡を水に溶解させてパージすることができる。従って水を被検査容器へ給水する際の跳ね返りや乱流により気泡が発生しても、耐圧検査時に水と気泡の圧縮率の違いによる被検査容器内の残留気泡による水量のばらつきが発生せず、正確な全増加量と恒久増加量の値を測定することができる。
【００３４】
特に被検査容器の全増加量、恒久増加量を測定するための媒体として利用する水を、微小気泡が浮遊する気相と液相が混在する状態から気相を実用上問題ない程度までパージして、液相のみの状態と等価と考えても良い状態にすることが可能となり、正確な測定データを得ることができる。
【００３５】
更に本発明ではサーボモータの回転数の差によって求めた被検査容器内の水の減量分あるいは増量分の重量を算出できるので、高い精度を有する測定を短時間で迅速に行うことが可能であり、目視による誤読等の個人差は発生せずに客観的な試験結果を得ることができて、高い精度を有する測定を短時間で迅速に行うことができる。
【００３６】
従って本発明によれば、被検査容器内の残留気泡によって生じる加圧用の水量のばらつきをなくして正確な全増加量と恒久増加量の測定値が得られ、客観的で高い精度を有する測定を短時間で迅速に行うことができる高圧ガス容器の非水槽式耐圧膨張試験方法を提供することができる。
【図面の簡単な説明】
【図１】本発明にかかる高圧ガス容器の非水槽式耐圧膨張試験におけるエアーパージ工程を示す概要図。
【図２】図１における検査ヘッドの詳細図。
【図３】被検査容器への給水部分の概略図。
【図４】図３における給水ヘッドの詳細図。
【図５】予備加圧工程における被検査容器の加圧パターン図。
【図６】予備加圧工程の有無による被検査容器の恒久増加量を比較して示すグラフ。
【符号の説明】
１…被検査容器
２…検査ヘッド
３…通水弁
４…排水弁
５…大気開放弁
７…サーボモータ
８…プランジャポンプ
９…圧力センサ
１２…予備加圧工程
１３…耐圧試験工程
２１…給水ヘッド
２２…給水パイプ
２３…給水バルブ
２４…排水パイプ
２５…電極スイッチ
整理番号 Ｐ３４７７[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container, and in particular, in order to realize accurate and practicable measurement accuracy, small bubbles floating in water to be filled in a container to be inspected are converted into water. The present invention relates to a method for performing an efficient and accurate non-aqueous tank type pressure expansion test by dissolving and purging.
[0002]
[Prior art]
In general, a high-pressure gas container used for liquefied petroleum gas or the like needs to be subjected to a pressure expansion test at the time of manufacture and every time a predetermined period elapses in order to inspect the safety in a pressurized state. This pressure expansion test is determined based on the permanent increase rate determined by the following equation (1). If the permanent increase rate is equal to or less than a certain value specified by law, the test is judged as passing. This is because a container having a smaller permanent increase rate has a larger restoring force and is more excellent in pressure resistance.
Permanent increase rate (%) = {Permanent increase amount (Δv) ÷ Total increase amount (ΔV)} × 100 (1)
[0003]
Here, the total increase (ΔV) is the volume increase due to the expansion of the gas container represented by V 2 −V 1 where V 1 is the volume of the gas container before pressurization and V 2 is the volume after pressurization. The permanent increase (Δv) is represented by V 3 −V 1 when the capacity of the gas container when the pressurization of the gas container is released is V 3, and the restoration of the gas container is incomplete. This is the amount of increase in capacity.
[0004]
A water tank type and a non-water tank type are known as test devices for measuring the total increase (ΔV) and the permanent increase (Δv). Among them, the water tank type pressure-resistant expansion test device is a high-pressure gas container to be inspected. Is placed in water in a closed water tank, and high-pressure water or the like is externally press-fitted into the high-pressure gas container to a predetermined high pressure, and the amount of water discharged from the water tank due to the expansion of the high-pressure gas container generated at this time. It measures by detecting the water level in the buret provided in communication with the water tank.
[0005]
However, in such a water tank type pressure expansion test apparatus, the amount of water discharged by expansion generated in the high-pressure gas container is considerably smaller than the amount of water to be filled in the water tank in principle. There is a disadvantage that the ratio of the signal to the measurement is small and the measurement accuracy is low. Further, in the water tank type pressure expansion test apparatus, since the amount of water used is large, the fluctuation amount due to the expansion and contraction of water caused by the environmental temperature is large. The amount of the fluctuation is an error with respect to the amount of water discharged due to the expansion of the high-pressure gas container to be detected. However, it is not rare that the magnitude of the error exceeds the signal amount, that is, the amount of water to be detected. This disadvantage is remarkable especially when the water tank is large.
[0006]
On the other hand, in the non-aqueous tank type pressure expansion test, the container to be inspected is filled with water in advance, and after sealing, water is pumped in by a plunger pump to increase the pressure in the container to be inspected and the pressure resistance is measured, and the amount of water sent is measured. This is a method of calculating the total increase by a predetermined formula, measuring the amount of water returned to the plunger pump when the pressure is reduced to the pressure before pressurization after pressurization, and obtaining the difference from the amount of water sent in as a permanent increase. According to this non-aqueous tank type pressure-resistant expansion test method, measurement with relatively high accuracy can be performed in a short time, but pulsation may occur in the gas container when the pressurizing pump is operated, and the water pressure is not sufficient. There is a problem that the measurement becomes stable and a measurement error easily occurs. Furthermore, the pressurized state is not stable due to the air remaining in the various pipes, and the accuracy of the pressure switch for detecting the pressing force is not always good, and the operation accuracy of the electromagnetic switching valve for opening and closing the various valves. Insufficient values also cause measurement errors.
[0007]
In response to the above, the applicant of the present invention has previously described, in Japanese Patent No. 3145888, a method in which a high-pressure gas container to be tested is fixed at a fixed position, and then a test head is fitted and fixed, and air provided at the other end of the test head is provided. After performing water injection and air bleeding from the water injection hole, the pressure in the high-pressure gas container is increased to a constant value using a plunger pump driven by the servomotor, and the position of the servomotor is read and maintained for a predetermined time. After that, the pressure in the high-pressure gas container is reduced, and the position of the servomotor when the water pressure in the high-pressure gas container falls to the value before pressurization is read. A non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container was proposed in which the amount and the permanent increase amount were obtained, and the permanent increase rate of the high-pressure gas container was calculated based on an arithmetic expression.
[0008]
According to such a non-aqueous tank-type pressure-resistant expansion test method, after the test head is fitted and fixed to the high-pressure gas container to be tested, water injection and air drainage from the air vent water injection hole provided at the other end of the test head are performed. Then, the pressure in the high-pressure gas container is increased to a certain value by the plunger pump, the position of the servomotor is read, and after maintaining for a predetermined time, the pressure in the high-pressure gas container is reduced to reduce the water pressure to the value before pressurization. By reading the position of the servomotor at this time, the total increase amount and the permanent increase amount of the high-pressure gas container are obtained from the read servomotor position, and the permanent increase rate can be calculated based on the arithmetic expression.
[0009]
[Problems to be solved by the invention]
However, when water is supplied to the container to be inspected in the non-aqueous tank type pressure expansion test, bubbles are generated due to the rebound and turbulence of the water in the container to be inspected. Due to the difference, the amount of water sent for the purpose of pressurization may vary due to residual air bubbles in the container to be inspected, and it may not be possible to accurately measure the total increase and the permanent increase. As a countermeasure, means for removing air bubbles by an air purge process before performing a pressure resistance test is considered, but since this air purge process is limited to visible ones in which bubbles to be purged float on the surface of the water, No countermeasures have been taken against microbubbles such that floating visual observations cannot be made, and there is a problem that only unstable data can be obtained. In particular, since there is no standard regarding the accuracy of the measurement data of the LPG container inspection machine, the opinion of the High Pressure Gas Safety Association that the permanent increase data of the acetylene cylinder (content: 41.7 liters) is 0.3 cc or less. Is used as a criterion for judging the validity of the measured data. However, in the past, this value could not be attained and the instability of the measured data makes it impossible to practically use the method as a pressure expansion test.
[0010]
Therefore, water used as a medium for measuring the total increase and permanent increase of the container to be inspected is purged from a state in which the gas phase in which microbubbles are suspended and a liquid phase are mixed to a level where there is no practical problem. However, it is important to obtain accurate data to obtain a state that can be considered equivalent to a state of only the liquid phase.
[0011]
Therefore, the present invention solves the problems of the conventional non-aqueous tank type pressure-resistant expansion test method and eliminates the variation in the amount of water for pressurization caused by residual air bubbles in the container to be inspected, thereby achieving an accurate total increase amount. The purpose of the present invention is to provide a non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container that can obtain a measured value of a permanent increase amount and an objective and highly accurate measurement in a short time and quickly. is there.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention purifies the pre-pressurizing step by purging air remaining in the upper part of the high-pressure gas container subjected to the test, and then pumping water with the inside of the pressurized system closed. Then, after purging the microbubbles floating in the water, increasing the pressure in the high-pressure gas container to a constant value and maintaining the pressure for a predetermined time, the total increase amount of the high-pressure gas container, and thereafter, the pressure is reduced, and The amount of permanent increase in the high-pressure gas container when the water pressure in the gas container drops to the value before pressurization is determined, and the permanent increase rate of the high-pressure gas container is calculated based on an arithmetic expression. A non-aqueous tank pressure expansion test method is provided as a basic means. The pre-pressurization step is performed at around 90% of the pressure test pressure and at 90% or less.
[0013]
Specifically, after fixing the high-pressure gas container to be tested at a fixed position, fitting and fixing the inspection head, bleeding and pouring water from the inspection head, the inside of the system under pressure is closed, and the pump is used. A pre-pressurization step is performed by sending water in, the microbubbles floating in the water are purged, and then the pressure in the high-pressure gas container is increased to a certain value using a plunger pump driven by the servomotor, and the servomotor is driven. After reading the position and maintaining the pressure for a predetermined time, the pressure in the high-pressure gas container is reduced, and the position of the servomotor when the water pressure in the high-pressure gas container falls to the value before pressurization is read. The total increase amount and the permanent increase amount of the high-pressure gas container are obtained from the position, and the permanent increase rate of the high-pressure gas container is calculated based on an arithmetic expression. Further, a non-aqueous tank-type pressure-resistant expansion test method in which the rotation speed of the servomotor is transmitted to a microcomputer and a total increase amount and a permanent increase rate of a high-pressure gas container for performing a pressure-resistant expansion test based on an arithmetic expression are calculated. I will provide a.
[0014]
According to such a non-aqueous tank-type pressure-resistant expansion test method, after water is supplied to the container to be inspected, air remaining in the upper part of the container to be inspected is purged by being pushed out to a drain valve, and then the drain valve is closed and then opened to the atmosphere. By opening the valve and purging the air remaining in the water supply pipe, the inside of the system to be pressurized is closed, and water is fed by a plunger pump as a pre-pressurization step, at around 90% of the pressure test pressure, and By increasing the pressure to 90% or less, the microbubbles floating in the water are dissolved in the water, and the microbubbles can be purged. After purging the microbubbles, the pressure is reduced by returning water from the pressurized system to the plunger pump, and the pressure is reduced to the pressure before pressurization, and the pre-pressurization step is completed. The amount of microbubbles can be reduced or eliminated by the pre-pressurizing step.
[0015]
After the pre-pressurization step, the inside of the pressurized system is closed, and then water is pumped by a plunger pump to increase the pressure.The state is maintained for a predetermined time, and the total increase is measured. Then, the pressure is reduced to a value, and a permanent increase, which is an increase in the volume of the container to be inspected, is calculated.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a specific embodiment of a non-aqueous tank pressure-resistant expansion test method for a high-pressure gas container according to the present invention will be described with reference to the drawings. In the present invention, in order to solve the above-mentioned problem, utilizing the fact that the dissolved concentration of gas in water changes with pressure, the air remaining in the upper part of the container to be inspected and the water supply pipe is purged by pouring water into the container to be inspected. It is characterized in that the pressurized system is closed and a preliminary pressurizing step is performed before the pressurization inspection.
[0017]
The processing steps of the non-aqueous tank type pressure expansion test method are roughly divided into four steps: a water supply step, an inspection step, a drainage step, and a drying step. FIG. 3 is a schematic view of a water supply portion to the container 1 to be inspected, 21 is a water supply head, 22 is a water supply pipe, 23 is a water supply valve, 24 is a drain pipe, and 25 is an electrode switch. As shown in the detailed view of FIG. 1, the lower end of the water supply head 21 is joined to the neck ring 26 of the container 1 to be inspected, the water supply pipe 22 is inserted to the bottom of the container 1 to be inspected, and the water supply valve 23 is opened. Supply water.
[0018]
When the container 1 to be inspected is filled with water, the water overflows from the outlet 27 of the water supply head 21 through the outlet 28 to the drain pipe 24. The electrode switch 25 provided on the drain pipe 24 is turned on by the overflowing water, and it is detected that the inside of the container 1 to be inspected is full. Therefore, the water supply valve 23 is closed to stop the water supply. After raising the water supply pipe 22, the water supply head 21 is separated from the container 1 to be inspected, and the water supply step is completed, and the container 1 to be inspected is sent to the next inspection step.
[0019]
Next, the inspection process of the container 1 to be inspected will be described. This inspection process includes two air purge processes and a pressure resistance inspection process, that is, a total of three processes. FIG. 1 is a schematic view showing an air purge step, wherein 1 is a container to be inspected after a water supply step has been completed, 2 is an inspection head, 3 is a water flow valve, 4 is a drain valve, and 5 is an atmosphere release valve. After fixing the inspection head 2 to the filled container 1 to be inspected, the water supply valve 3 and the drain valve 4 are opened, the air release valve 5 is closed, and then the water supply 6 is performed through the water supply valve 3. 7 is a servomotor, 8 is a plunger pump, and 9 is a pressure sensor.
[0020]
Water is supplied from the test head 2 shown in an enlarged manner in FIG. 2 to the container 1 through a water injection port 10 protruding below the neck ring 26 of the container 1 to be inspected, and air remaining in the upper part of the container 1 is drained. 1 to the drain valve 4 to purge the air. Then, the drain valve 4 shown in FIG. 1 is closed, and the air release valve 5 is opened to purge air remaining in the water supply pipe. The opening valve 5 is closed, and the air purge step is completed.
[0021]
Next, the process proceeds to a pre-pressurizing step which is a characteristic step of the present invention. First, from the state shown in FIG. 1, the water flow valve 3, the drain valve 4, and the atmosphere release valve 5 are closed to close the pressurized system. Then, water is fed into the sealed pressurized system by the plunger pump 8 to increase the pressure to around 90% of the pressure resistance test pressure and to 90% or less. By applying pressure to the water while maintaining the state for about 5 seconds, the microbubbles floating in the water are dissolved in the water, and the microbubbles can be purged. After purging the microbubbles, the pressure is reduced by returning water from the pressurized system to the plunger pump 8, and the pressure is reduced to the pressure before pressurization, and the pre-pressurization step is completed.
[0022]
Gases that are relatively insoluble in water satisfy Henry's law expressed by equation (2).
p = HC (2)
Here, p is the partial pressure of the solute gas in the gas phase, C is the liquid concentration, and H is the Henry's law constant.
[0023]
Therefore, even if the gas phase and the liquid phase are in an equilibrium state at atmospheric pressure, the equilibrium concentration is increased by pressurization, and the dissolution of the gas starts at a new equilibrium point. If this gas is replaced with microbubbles floating in water, the amount of microbubbles can be reduced or eliminated by applying pressure.
[0024]
After the completion of the pre-pressurizing step, a withstand voltage inspection step is performed. This pressure resistance inspection step is performed by closing the water flow valve 3, the drain valve 4, and the atmosphere release valve 5, making the pressurized system closed, and sending water into the sealed pressurized system by the plunger pump 8. Then, the pressure is increased to 3 MPa of the pressure resistance test pressure, and the pressure is increased for 30 seconds. After the pressure is applied for 30 seconds, the total increase is measured, and after the measurement, the pressure is reduced to the pressure before pressurization, and the permanent increase, which is the volume increase of the container 1 to be inspected, is calculated.
[0025]
Briefly describing a specific method of the pressure resistance expansion test, the test container 1 was fixed at a fixed position, then the test head 2 was fitted and fixed, and air was injected from the test head 2 as described above. Thereafter, a pre-pressurizing step is performed by sending water with the inside of the system to be pressurized in a sealed state, purging microbubbles floating in the water, and then inspecting using a plunger pump 8 driven by a servomotor 7. The position of the servomotor 7 is read by increasing the pressure in the container 1 to a constant value, and after a predetermined time is maintained, the pressure in the container 1 to be inspected is reduced and the servo when the water pressure falls to the value before pressurization is performed. The position of the motor 7 is read, and the total increase (ΔV) and the permanent increase (Δv) of the container 1 to be inspected are obtained from the read positions of the servo motors 7. Calculate (%).
[0026]
Further, the number of rotations of the servomotor 7 is transmitted to a microcomputer (not shown), and the total increase (ΔV) and the permanent increase (Δv) of the container 1 to be inspected are obtained based on an arithmetic expression. The rate of increase (%) can also be determined.
[0027]
Next, as a drainage process, compressed air is sent from the neck ring 26 of the container 1 to be inspected, and water used for the pressure resistance inspection is drained using the water supply pipe 22 reaching the bottom of the container 1 to be inspected. Move to the drying step. The drying step includes a heating drying step and an air replacement step. The heating drying step is a step of drying water remaining on the wetted wall surface and the bottom of the container 1 to be inspected by steam by heating, and the air replacement step is a heating drying step. This is a step of sending dry compressed air after completion to replace the steam remaining in the container 1 to be inspected.
[0028]
Here, the pre-pressurizing step, which is a characteristic step of the present invention, will be described. FIG. 5 is a pressurizing pattern diagram in which the vertical axis indicates the inspection pressure (MPa) and the horizontal axis indicates the inspection time (sec). By pre-pressurizing the container 1 to be inspected by the pre-pressurizing step 12 at about 2.5 MPa for a time a to reduce microbubbles floating in water, the pressure test step 13 is to pressurize at about 3 MPa for a time b. , The measured values of ΔV (total increase) and Δv (permanent increase) are obtained. Time a is about 5 seconds and time b is 30 seconds or more. It is a feature of the present invention that the pressure test step 13 is performed after the effect of the microbubbles can be sufficiently ignored by performing the preliminary pressurizing step 12.
[0029]
The dissolved gas is re-evaporated during the depressurization 12a in the pre-pressurizing step 12, but it takes time to reach a new equilibrium point. Can be reduced from a practical level to a level that does not cause any problem.
[0030]
FIG. 6 is a graph comparing the permanent increase of acetylene cylinders with and without the pre-pressurizing step 12, in which the vertical axis indicates the permanent increase (cc) and the horizontal axis indicates the number of inspections of the same acetylene cylinder. . The graph 14 shows the measured value of the permanent increase when the pre-pressurizing step 12 is not performed, and the graph 15 shows the measured value of the permanent increase when the pre-pressurizing step 12 is performed. The condition of the preliminary pressurizing step 12 was a pressure of 2.5 MPa for 5 seconds.
[0031]
According to FIG. 6, by performing the pre-pressurizing step 12, the measured data of the permanent increase (cc) is reduced to 0.3 cc or less, and the dispersion of the measured data is reduced to obtain stable data. This can contribute to the practical application of the non-aqueous tank type pressure expansion test.
[0032]
As described above, the non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container according to the present invention can be established. This test method does not require a water tank, and determines the volume increase of the container 1 to be inspected by measuring the amount of water sent during pressurization, and the volume decrease by measuring the amount of water returned from the container 1 to be inspected during depressurization. The permanent increase rate (%) can be measured by calculation. The non-aqueous tank type pressure-resistant expansion test has the features that, since there is no water tank, the configuration itself is downsized, the manufacturing cost is low, and maintenance and management labor is reduced.
[0033]
【The invention's effect】
As described above in detail, according to the non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container according to the present invention, after water is supplied to the container to be inspected, air remaining in the upper part of the container to be inspected and the water supply pipe is purged. After that, the inside of the system to be pressurized is closed, and the preliminary pressurizing step is performed, whereby the microbubbles floating in the water can be dissolved and purged. Therefore, even if bubbles are generated due to rebound or turbulence when water is supplied to the container to be inspected, there is no variation in the amount of water due to residual bubbles in the container to be inspected due to a difference in compression ratio between water and bubbles during the pressure resistance test. , It can measure accurate total and permanent increment values.
[0034]
In particular, purify the water used as a medium for measuring the total increase and the permanent increase of the container to be inspected from a state in which the gas phase in which the microbubbles are suspended and the liquid phase to the extent that there is no practical problem in the gas phase. As a result, a state that can be considered equivalent to a state of only the liquid phase can be obtained, and accurate measurement data can be obtained.
[0035]
Further, in the present invention, since the weight of the reduced or increased amount of water in the container to be inspected determined by the difference in the number of rotations of the servomotor can be calculated, it is possible to quickly perform highly accurate measurement in a short time. In addition, an objective test result can be obtained without causing individual differences such as visual misreading, and a highly accurate measurement can be performed quickly in a short time.
[0036]
Therefore, according to the present invention, accurate measurement values of the total increase amount and the permanent increase amount can be obtained without variations in the amount of water for pressurization caused by residual air bubbles in the container to be inspected, and a measurement having an objective and high accuracy can be obtained. It is possible to provide a non-aqueous tank type pressure-resistant expansion test method for a high-pressure gas container that can be performed quickly in a short time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an air purging step in a non-aqueous tank pressure-resistant expansion test of a high-pressure gas container according to the present invention.
FIG. 2 is a detailed view of the inspection head in FIG.
FIG. 3 is a schematic diagram of a portion for supplying water to a container to be inspected.
FIG. 4 is a detailed view of a water supply head in FIG. 3;
FIG. 5 is a pressurization pattern diagram of a container to be inspected in a preliminary pressurization step.
FIG. 6 is a graph showing a comparison of a permanent increase amount of a container to be inspected depending on whether or not a pre-pressurizing step is performed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inspection container 2 ... Inspection head 3 ... Water flow valve 4 ... Drain valve 5 ... Atmospheric release valve 7 ... Servo motor 8 ... Plunger pump 9 ... Pressure sensor 12 ... Pre-pressurization process 13 ... Pressure test process 21 ... Water supply head 22 ... water supply pipe 23 ... water supply valve 24 ... drainage pipe 25 ... electrode switch reference number P3377
