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1、 外文原文： Water-based hydraulic systems Water-based hydraulic systems traditionally have been used in hot-metal areas of steel mills. The obvious advantage of water systems in these industries is their fire resistance. Water-based hydraulic systems also have obvious cost advantages over oil-based fl

2、uid. First, non-toxic, biodegradable synthetic additives for water cost $5 to $6 per gallon. One gallon of concentrate can make 20 gallons of a 5% solution, so the cost of water-based hydraulic fluid actually can be less than 30 cents per gallon. Considering the costs associated with preventing and

3、 cleaning up environmental contamination, water-based hydraulic systems hold the potential for tremendous cost savings at the plant level. Oil that has leaked already becomes a very important problem. It must be collected, properly contained. Water containing synthetic additives, however, can by dum

4、ped into plant effluent systems. Cost savings at the plant level don#39 stop at the lower cost of the fluid and its disposal. Because water-based hydraulic fluid consists of 10 parts water and one part synthetic additive, 5 gallons of additive mixes with water to make 100 gallons of water-based flu

5、id. A 50gallon container is certainly easier to handle than two 55-gallon drums, so warehousing is simpler, cleaner, and less cluttered. Transportation costs also are lower. Other potential plant-wide savings include improved safety for workers because the water-based fluid is non-toxic as well as

6、non-flammable. These attributes can reduce plant insurance rates. Spills cost less to clean up because granular absorbents or absorbent socks are unnecessary. Water is hot again The oil embargo in the 1970s sparked interest in water-based fluids as a less-costly alternative to oils. Even the most e

7、xpensive water additives became attractive when designers learned that one gallon of concentrate would make 20 gallons of fluid. As oil prices gradually dropped, so did interest in water-based hydraulics. In retrospect, interest in water-based fluids centered on their cost saving potential. Most de

8、signers lost interest when they discovered that they could not just change the fluid in their systems from oil to water without making other substantial changes. They then become reluctant to accept other disadvantages read substantial changes of switching over to water-based hydraulics. What were

9、viewed as disadvantages were really different rules that apply to water-based hydraulic systems? Designers probably resisted learning more about water-based hydraulics because they were intimated by all the work required to lean about how to design a new system or retrofit an older system. By closin

10、g their minds to this different technology, they missed the many other advantages of water-based fluid beyond initial cost. Now that environmental concerns have added disposal costs to the price of hydraulic fluids, water-based hydraulics has again become a hot topic. Fighting freeze Water-based h

11、ydraulic systems do, of course, have limits to their applications. One limitation is the potential of freezing. This possibility is probably the most significant blockade to more widespread application of water-based systems, especially in the mobile equipment industry. Long wall mining is by far th

12、e largest sector of mobile equipment that has been able to take advantage of water-based systems. Temperatures underground do not approach the freezing point of water, and fire resistance is essential. Mobile and even marine equipment used in temperate climates could cash in one the advantages of wa

13、ter based systems, but there is no guarantee that such equipment always will be used in above-freezing temperatures. Nevertheless, adding an anti-freeze to a water-based fluid can depress its freezing temperature to well below 32°F. Ethylene glycol used in automotive anti-freeze is toxic and i

14、s not biodegradable, so its use for anti-freeze in water-based hydraulic fluid would defeat the environmental advantage water-based fluid has. There is an alternative. Propylene glycol is not toxic and is biodegradable. It costs more than ethylene glycol and is not quite as effective antifreeze, so

15、 it must be used in slightly higher concentrations. Two more techniques to reduce freezing potential are to keep fluid circulating continuously and use hose where practical. Sealing the system Two more perceived problems with water hydraulic systems are bacterial infestation and difficulty in main

16、tain proper concentrations. Sealing the system from atmosphere can hold bacterial growth in check. Addition of an anti-bacterial agent to the fluid can have a lasting effect on preventing bacterial buildup if air is excluded from the system. A sealed reservoir eliminates another problem suffered by

17、 many hydraulic systems: water ingression. This addresses another misconception about water-based systems: water-based systems not sealed from the atmosphere must be closely monitored to ensure that the additive concentration stays within tolerance. That is because water evaporates from the reservoi

18、r more readily than the additive does. Consequently, water evaporation causes the additive concentration to increase. When new fluid is added to a system, samples of the existing fluid must be taken to determine the concentration of additive in solution. These results then reveal the ratio of additi

19、ve to fluid that must be added so that fluid concentration is correct. With a system that seals fluid from the atmosphere, the evaporation problem is virtually eliminated. Fluid that escapes by leakage is a solution containing water and additive. Therefore, the quantity of fluid in the system chang

20、es, but concentration does not. System fluid is replenished simply by adding a pre-mixed solution of water and additive to the reservoir. Special considerations Water-based hydraulic systems can be more prone to pump cavitation if they are not properly designed. Generous porting and other passagew

21、ays should be provided to keep fluid velocities below 20 ft. /sec preferably, below 15 ft./sec in pressure lines. Velocity in suction lines, in general, should not exceed 2-3 ft. /sec. Velocities in return lines should be held below 5-10ft/sec. Higher return velocities can promote foaming when fluid

22、 re-enters the reservoir. Components should also be carefully sized because rapid changes in fluid pressure and velocity can cause dissolved air to precipitate from solution and cause damage similar to that produced by capitations. An important consideration for water-based systems is that major co

23、mponents should be designed specifically for use with water fluid, rather than modified from versions originally intended for oil service. Tubing, hose, and fittings usually can be identical to those for oil systems. Pumps, valves, and actuators for water service, however, exhibit some significant d

24、ifferences from components for oil systems. Pump gears, for example, should be made of super-hard alloys to resist wear. A pump#39 gear face should be wider than that of an oil pump because water #39 low viscosities requires a larger area to form an adequate lubricant film. Cylinders used in water s

25、ystems should have bronze-clad pistons to minimize wear between pistons and cylinder walls. Spring- or O-ring-energized seals should be used to minimize leakage across the piston. Valves for water Valves for water-based fluid usually are packed with seals separating metal parts to prevent metal-to

26、-metal contact. This is because water even with lubricant additives does not provide the full-film lubrication of oil. Metal surfaces in relative motion in valves for water-based fluid are separated by bearing-type materials. Valves for water service also are slightly larger than those for oil. Thi

27、s may be another reason why water-based systems have not gained wide acceptance. Originally, the larger size of components for water-based fluid created a handicap when designing systems, and more costly construction inflated prices of valves for water-based fluid to three times or more that of valv

28、es for oil. Now, however, valve sizes are comparable to those for oil. Many valves are available with standard NFPA footprints. The price differential has also become less. Components for water-based fluid still may cost perhaps 3% more than those for oil systems, but this may be a bargain when you

29、consider the cost-saving potential of water-based systems. Fluid leakage Leakage continues to be a nagging problem in many hydraulic systems. New seal materials and designs, and O-ring face-seal fittings are powerful weapons in the battle against leakage. But the battle is far from over because of

30、 misapplication, improper installation, or simple lack of understanding. Although there#39; s no excuse for leakage in most systems, it still occurs. Assuming that leakage will not be eliminated in the near future, water-based fluid can dramatically reduce the costs associated with leakage. Interna

31、l leakage can be just as wasteful. This leakage can carburize the oil by generating heat. Internal leakage typically is routed back to tank, so this technique transforms mechanical energy into heat instead of useful work. Using a stainless steel spool with PTFE seals in a valve for water-based fluid

32、 eliminates the need for clearance between moving components. Because there is no clearance, there is no internal leakage. But beyond the obvious and intangible costs of fluid leakage, disposing of the fluid that has leaked from a system becomes a concern. Allowing hydraulic oil to enter plant effl

33、uent systems becomes an expensive proposition when removal and disposal costs are considered. Realizing that cleanup and disposal costs will only go up, and that the price of oil is unstable suggests that water-based hydraulics can be an economical solution to environmental problems. 中文

34、翻譯： 水基液壓系統(tǒng) 傳統(tǒng)上水基液壓系統(tǒng)已經(jīng)應(yīng)用在鋼鐵廠煉鐵領(lǐng)域。這些產(chǎn)業(yè)中水基液壓系統(tǒng)的明顯的優(yōu)點(diǎn)是它們的耐火性。而且水基液壓系統(tǒng)在費(fèi)用上也優(yōu)于油基的液壓系統(tǒng)。首先，無毒的、可被生物分解的綜合性添加劑每加侖花費(fèi)5到6美元。一加侖集中可生成20加侖的5%溶液，因此實(shí)際上水基液壓流體的費(fèi)用可以比油基的每加侖少30分。 在工廠的水平下，考慮到相關(guān)費(fèi)用、防止和清理環(huán)境的污染，水基液壓系統(tǒng)擁有節(jié)省巨大成本的潛力。液壓油的泄漏已經(jīng)成為一個(gè)非常重要的問題。它必須被收集、妥善控制。不過，含有合成添加劑的水，可以傾倒入工廠的污水系統(tǒng)。 在工廠水平下，節(jié)省成本不停留在流體的較低成本及其處理上。因?yàn)樗?/p>

35、壓液由十部分水和一部份合成添加劑，5加侖添加劑與水的混合物構(gòu)成100加侖水基流體。50加侖的容器當(dāng)然比兩個(gè)55加侖的桶更容易處理，因此儲(chǔ)藏更簡(jiǎn)單、更清潔、更不凌亂，運(yùn)輸成本也較低。 其他工廠范圍下潛在的節(jié)約是為工人改善安全，因?yàn)樗菏遣缓拘裕⑶曳且兹?。這些特點(diǎn)可以減少工廠的保險(xiǎn)費(fèi)率。泄漏的成本比清理低，因?yàn)椴辉傩枰w粒吸收劑或吸附棉條。水基流體再次變成“熱門話題” 在20世紀(jì)70年代石油禁運(yùn)引發(fā)了較低成本的水基液壓流體替代高昂的液壓油的興趣。當(dāng)設(shè)計(jì)師們獲悉，一加侖聚合物可以制造出二十加侖的流體時(shí)，即使是最昂貴的水添加劑都更有吸引力。 由于石油價(jià)格逐漸的回落，因此人們對(duì)水基液壓也沒有

36、那么大的興趣了。回想起來，對(duì)水基流體的興趣集中在其節(jié)省成本的潛力上。當(dāng)設(shè)計(jì)師發(fā)現(xiàn)他們不能在他們的系統(tǒng)中改變流體從液壓油到水的狀況并且也沒有其他重大的改變時(shí)，他們就失去了興趣。然后，他們不情愿的接受其他的“缺點(diǎn)”–了解到很大的變化–又切換到水基液壓。 適用于水基液壓系統(tǒng)的不同的規(guī)則被認(rèn)為是缺點(diǎn)。設(shè)計(jì)師可能不愿意學(xué)習(xí)更多關(guān)于水基液壓，因?yàn)樗麄儽话凳?，所有的工作需要依靠如何設(shè)計(jì)一個(gè)新的系統(tǒng)或改造舊系統(tǒng)的知識(shí)。因?yàn)樗麄兘Y(jié)束了對(duì)這另外技術(shù)的思維，他們錯(cuò)過了除水基流體初始成本以外的許多其他的優(yōu)點(diǎn)?，F(xiàn)在，環(huán)境問題，增加了液壓油處理成本的價(jià)格，水基液壓便再次成為熱門話題。 抵抗凝固 當(dāng)然，水基液壓系統(tǒng)確

37、實(shí)在應(yīng)用上有它的局限性。一個(gè)限制就是潛在的凝固。這個(gè)可能性可能是更廣泛地應(yīng)用水基系統(tǒng)，特別是在移動(dòng)設(shè)備業(yè)最重要的阻礙。長(zhǎng)壁開采法是迄今為止最大的能夠充分利用水基系統(tǒng)的移動(dòng)設(shè)備部門。地下的溫度不接近水的凝點(diǎn)和耐火性是必不可少的條件。用于溫帶氣候海上設(shè)備和移動(dòng)設(shè)備獲利于水基系統(tǒng)的優(yōu)點(diǎn)，但不能保證這些設(shè)備將始終用在上述凝固溫度。 不過，給水基流體加入防凍液可以使其凝固溫度遠(yuǎn)低于32華氏度。用在汽車上的防凍液-乙二醇-是有毒的，是不能生物降解的，因此它在水基液壓中添加防凍液將擊敗水基液壓流體在環(huán)境上的優(yōu)勢(shì)。 有一個(gè)替代的方法。丙二醇是沒有毒性，而且是可生物降解的。它比乙二醇花費(fèi)更多，并且是不太有效

38、的一種防凍液，因此它必須使用較高濃度的溶液。減少凝固潛力的另外兩個(gè)技術(shù)是要保持流體的不斷循環(huán)和在實(shí)際中使用膠管。 系統(tǒng)的密封 水基液壓系統(tǒng)的兩個(gè)個(gè)容易被察覺的問題是細(xì)菌的大批出沒，并且很難保持適當(dāng)?shù)臐舛?。大氣下的密封系統(tǒng)在控制中可容納細(xì)菌成長(zhǎng)。此外，如果從系統(tǒng)排除空氣，一個(gè)抗菌劑的流體能對(duì)防止細(xì)菌的增長(zhǎng)有一個(gè)持久的影響。 一個(gè)被密封的水箱消除許多液壓系統(tǒng)遭受的另一個(gè)問題：水的進(jìn)入。這說明關(guān)于水基系統(tǒng)的另一個(gè)誤解：沒有從大氣中密封的水基系統(tǒng)，必須密切監(jiān)察，以確保該添加劑濃度保持在在允許的范圍之內(nèi)。這是因?yàn)樗忍砑觿└菀讖乃湔舭l(fā)。因此，水分蒸發(fā)導(dǎo)致添加劑濃度增加。當(dāng)新液體添加到系統(tǒng)時(shí)，現(xiàn)

39、有的流體樣本必須采取措施，以確定一定濃度的添加劑在溶液中。這些結(jié)果顯示，添加劑在流體中的比例必須補(bǔ)充，使流體的濃度是合適的。 與大氣隔絕的密封的流體系統(tǒng)，實(shí)際上消除了蒸發(fā)問題。泄漏的液體是包含水和添加劑的。所以，系統(tǒng)液體的量在發(fā)生變化，但濃度沒有變化。 系統(tǒng)流體通過增加水和添加劑的一種預(yù)先混合重新補(bǔ)充到水箱。 特殊的考慮 如果水基液壓系統(tǒng)沒有正確的設(shè)計(jì)，他們可能更容易使水泵汽蝕。應(yīng)提供通暢的通道，保持流體速度低于20英尺/秒，最好是在壓力線低于15英尺/秒。在一般情況下，吸油管的速度，不應(yīng)超過2–3英尺/秒。在回油管的速度應(yīng)低于5到10英尺/秒。當(dāng)流體再進(jìn)入水箱時(shí)，較高的回油管速度可以促

40、進(jìn)發(fā)泡。零部件也應(yīng)注意其規(guī)格，因?yàn)榱黧w壓力和速度急劇變化可能造成溶解氣體和造成類似氣蝕的損傷。 對(duì)水基的系統(tǒng)的重要考慮是應(yīng)該明確設(shè)計(jì)主要元件為水基流體所使用，而不是修改最初供油服務(wù)的系統(tǒng)。油管，膠管，及配件，通常對(duì)這些油基液壓系統(tǒng)可以相同。但是，水泵，閥，執(zhí)行器和供水裝置，存在著一些重大不同。例如，齒輪泵，應(yīng)做出超硬合金抗磨損。泵的齒輪比一個(gè)油泵應(yīng)更廣泛，因?yàn)樗牡驼扯刃枰粋€(gè)更大的范圍，以形成一個(gè)足夠的潤(rùn)滑膜。使用在水基系統(tǒng)中的缸應(yīng)該有青銅做的活塞，以減少活塞和缸壁之間的磨損。彈簧或O型圈的密封用來減少活塞的滲漏。 水基液壓閥 水基的流體的閥通常是加了密封件，用于分離金屬零件，以防止金

41、屬-金屬接觸。這是因?yàn)樗?甚至與潤(rùn)滑油添加劑-沒有提供完整的潤(rùn)滑油膜。 水基裝置用的閥的價(jià)格也有少許大于油基裝置的。這可能是另一個(gè)原因，水基系統(tǒng)沒有得到廣泛的接受。本來，當(dāng)設(shè)計(jì)系統(tǒng)時(shí)，面積較大的元件水基流體創(chuàng)建了一個(gè)障礙，并且更加昂貴的制造價(jià)格使水基液壓閥的價(jià)格提高了3倍或更多。不過，現(xiàn)在閥大小和油基系統(tǒng)的相當(dāng)。許多閥可達(dá)到美國(guó)國(guó)家防火協(xié)會(huì)標(biāo)準(zhǔn)。價(jià)格差異也較少。水基液壓元件仍可能花費(fèi)比油基系統(tǒng)高3 ％以上，但當(dāng)考慮到水基系統(tǒng)節(jié)省成本的潛力，這樣做可能會(huì)得到更多的實(shí)惠。 流體的泄露 在許多液壓系統(tǒng)中泄漏仍然是一個(gè)惱人的問題。新的密封材料及設(shè)計(jì)，及O型圈，是解決密封裝置泄漏的功能強(qiáng)大的武器。

42、由于誤用，安裝不當(dāng)，或缺乏簡(jiǎn)單的了解，泄漏的問題仍未解決。雖然在大多數(shù)的系統(tǒng)中沒有任何理由泄漏，但它仍然出現(xiàn)。假設(shè)不解決泄漏，在不久的將來，水基液可以大大降低泄漏的相關(guān)費(fèi)用。 內(nèi)部泄漏是很浪費(fèi)的。這種泄漏能能使溫度升高，從而使液壓油碳化。內(nèi)部泄漏通常是泄露回容器的，因此這一技術(shù)轉(zhuǎn)化成機(jī)械能的熱，這并不是有益的工作。在一個(gè)水基液壓閥運(yùn)動(dòng)部件中采用不銹鋼閥芯聚四氟乙烯密封。因?yàn)闆]有間隙，所以就不存在內(nèi)部泄漏。 但除了明顯的和無形的液漏成本外，處理已泄漏液體已經(jīng)成為一個(gè)被人關(guān)注的問題。考慮到除去或取消成本時(shí)，允許液壓油進(jìn)入污水廠系統(tǒng)成為一個(gè)昂貴的主張。實(shí)現(xiàn)這一清理和處置成本只會(huì)上升，并且石油價(jià)格的不穩(wěn)定表明，水基液壓可以成為一個(gè)利于解決環(huán)境問題比較經(jīng)濟(jì)的辦法。