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止回閥是能自動(dòng)阻止流體倒流的閥門。止回閥的閥瓣在流體壓力作用下開啟，流體從進(jìn)口側(cè)流向出口側(cè)。當(dāng)進(jìn)口側(cè)壓力低于出口側(cè)時(shí)，閥瓣在流體壓差、本身重力等因素作用下自動(dòng)關(guān)閉以防止流體倒流。
止回閥一般分為升降式、旋啟式等幾種類型。
升降式止回閥的結(jié)構(gòu)一般與截止閥相似，其閥瓣沿著通道中心線作升降運(yùn)動(dòng)，動(dòng)作可靠，但流體阻力較大，適用于較小口徑的場(chǎng)合。升降式止回閥可分為直通式和立式兩種。直通式升降式止回閥一般只能安裝在水平管路，而立式升降止回閥一般應(yīng)安裝在垂直管路。
旋啟式止回閥的閥瓣繞轉(zhuǎn)軸作旋轉(zhuǎn)運(yùn)動(dòng)。其流體阻力一般小于升降式止回閥，它適用于較大口徑的場(chǎng)合。旋啟式止回閥根據(jù)閥瓣的數(shù)目可分為單瓣旋啟式、雙瓣旋啟式及多瓣旋啟式三種。單瓣旋啟式止回閥一般適用于中等口徑的場(chǎng)合。大口徑管路選用單瓣旋啟式止回閥時(shí)，為減少水錘壓力，*好采用能減小水錘壓力的緩閉止回閥。雙瓣旋啟式止回閥適用于大中口徑管路。對(duì)夾雙瓣旋啟式止回閥結(jié)構(gòu)小、重量輕，是一種發(fā)展較快的止回閥；多瓣旋啟式止回閥適用于大口徑管道路。
主要零件材料及性能規(guī)范
|
主 要 零 部 件 |
閥體、閥蓋、搖桿 |
WCB |
CF8 |
CF8M |
WC6、WC9 |
|
閥瓣 |
WCB堆Cr13或硬質(zhì)合金 |
CF8堆硬質(zhì)合金 |
CF8M堆硬質(zhì)合金 |
WC6、WC9堆硬質(zhì)合金 | |
|
閥座 |
25堆Cr13或硬質(zhì)合金 |
304堆硬質(zhì)合金 |
316堆硬質(zhì)合金 |
20Cr1MoV堆硬質(zhì)合金 | |
|
墊片 |
軟鐵、XB450 |
聚四氟乙烯 |
聚四氟乙烯 |
不銹鋼+耐酸石棉纏繞墊 | |
|
螺栓 |
35CrMoA |
35CrMoA |
35CrMoA |
25Cr1Mo1V | |
|
螺母 |
45 |
45 |
45 |
35CrMoA | |
|
主要參數(shù) |
適用介質(zhì) |
油品、水、蒸汽 |
硝酸類 |
醋酸類 |
油品、水、蒸汽 |
|
適用溫度 ℃ |
≤425 |
≤200 |
≤200 |
≤550 |
|
型號(hào) |
公稱 通徑 NPS(in) |
壓力級(jí) Class |
主要結(jié)構(gòu)尺寸(mm) |
閥體 材料 |
性能規(guī)范 | |||||
|
D |
D1 |
L |
L1 |
H |
適用溫度(℃) |
適用介質(zhì) | ||||
|
SFH |
2" |
150 |
|
|
203 |
|
170 |
WCB |
≤425 |
水、油品、蒸氣等 |
|
" |
3" |
" |
|
|
241 |
|
185 |
" |
" |
" |
|
" |
4" |
" |
|
|
292 |
|
215 |
" |
" |
" |
|
" |
6" |
" |
|
|
356 |
|
260 |
" |
" |
" |
|
" |
8" |
" |
|
|
495 |
|
300 |
" |
" |
" |
|
" |
10" |
" |
|
|
622 |
|
350 |
" |
" |
" |
|
" |
12" |
" |
|
|
699 |
|
400 |
" |
" |
" |
|
" |
14" |
" |
|
|
787 |
|
450 |
" |
" |
" |
|
" |
16" |
" |
|
|
864 |
|
480 |
" |
" |
" |
|
" |
18" |
" |
|
|
978 |
|
540 |
" |
" |
" |
|
" |
20" |
" |
|
|
978 |
|
600 |
" |
" |
" |
|
" |
24" |
" |
|
|
1295 |
|
680 |
" |
" |
" |
|
SFH |
2" |
300 |
|
|
267 |
|
170 |
WCB |
≤425 |
水、油品、蒸氣等 |
|
" |
3" |
" |
|
|
318 |
|
215 |
" |
" |
" |
|
" |
4" |
" |
|
|
356 |
|
235 |
" |
" |
" |
|
" |
6" |
" |
|
|
445 |
|
300 |
" |
" |
" |
|
" |
8" |
" |
|
|
533 |
|
340 |
" |
" |
" |
|
" |
10" |
" |
|
|
622 |
|
350 |
" |
" |
" |
|
" |
12" |
" |
|
|
711 |
|
420 |
" |
" |
" |
|
" |
14" |
" |
|
|
838 |
|
480 |
" |
" |
" |
|
" |
16" |
" |
|
|
864 |
|
520 |
" |
" |
" |
|
" |
18" |
" |
|
|
978 |
|
600 |
" |
" |
" |
|
" |
20" |
" |
|
|
1016 |
|
670 |
" |
" |
" |
|
" |
24" |
" |
|
|
1346 |
|
750 |
" |
" |
" |
|
SFH |
2" |
600 |
|
|
292 |
|
175 |
WCB |
≤425 |
水、油品、蒸氣 |
|
" |
3" |
" |
|
|
356 |
|
230 |
" |
" |
" |
|
" |
4" |
" |
|
|
432 |
|
295 |
" |
" |
" |
|
" |
6" |
" |
|
|
559 |
|
360 |
" |
" |
" |
|
" |
8" |
" |
|
|
660 |
|
400 |
" |
" |
" |
|
" |
10" |
" |
|
|
787 |
|
460 |
" |
" |
" |
|
" |
12" |
" |
|
|
838 |
|
520 |
" |
" |
" |
|
" |
14" |
" |
|
|
889 |
|
560 |
" |
" |
" |
|
" |
16" |
" |
|
|
991 |
|
650 |
" |
" |
" |
|
" |
18" |
" |
|
|
1092 |
|
730 |
" |
" |
" |
|
" |
20" |
" |
|
|
1194 |
|
800 |
" |
" |
" |
|
" |
24" |
" |
|
|
1397 |
|
900 |
" |
" |
" |
