最近，我在美国，见到Constantinou 教授。 提到FIP等公司生产的使用阀门和油库的阻尼器。 他给我了这封他写给一位俄国专家的信。 并说“ 这种很差的产品”，用不了几年就会损坏。 他提到2008年前法国-美国合资公司Jarrett-Enidine， 应用的就是这种技术，在美国加州州政府工程中供货安装的阻尼器质量出现严重问题。256个阻尼器中的30个都产生阀门等质量问题。在“退货”、“重新加工”、“陷入官司”等消息后，最终传来该公司破产的惊人消息。http://okok.org/forum/viewthread ... page%3D3&page=1。

我对这种使用油库和阀门的阻尼器并不十分了解。 Constantinou 教授写的有的问题还在学习。但我愿意把原文先公布出来，供国内有关专家、生产商参考。
我们曾经介绍过油阻尼器和粘滞阻尼器的差别，  http://okok.org/forum/viewthread.php?tid=273032  重新看一遍，对了解Constantinou 教授的一些看法，应该还是有帮助的。

延用我上一篇博客的办法， 不做翻译，原文登载，避免不必要的曲解。有愿意要看中文的朋友，可以个别和我们联系。

From: Michael Constantinou <constan1@buffalo.edu>
Sent: Monday, March 19, 2012 3:04 PM
To: 'louknes@stand.gr'
Subject: RE: ΑΠΟΤΕΛΕΣΜΑΤΑ ΔΟΚΙΜΩΝ
Nestor:
Here is my opinion. I have been dealing with dampers for the last 22 years and have been inspector of dampers for some 20 projects. Most of this knowledge I gained from Douglas Taylor, President of Taylor Devices and certainly the most knowledgeable person on damper design and manufacture.
Dampers with accumulators are problematic. They will require maintenance, they may fail and they are easy to
vandalize or break by accident. Specifically:
1. Accumulators are used for either thermal volume make‐up, leakage volume make‐up, rod displacement make‐up‐ or any combinations of these.
2. The accumulator must have a series of valves/check valves/tiny orifices in it‐ otherwise the damper will explode when cycled. The check valve, on the accumulator intake, must close when flow is going into the accumulator and have a tiny
bleed hole in it to allow only a limited flow volume into the accumulator when the damper is at high pressure during a seismic event‐ or when the train is braking on the track section the damper is attached to. This tiny hole could also be replaced by a flow control valve. The check valve(s) must open on accumulator exhaust to allow displaced rod volume, leakage volume, or thermal volume to go back into the damper. If any of these valves ever stick‐ the damper will fail unsafely‐ either with zero damping force, or the opposite‐ when it will try to get to infinite damping force‐ exploding before this occurs. Over time‐ all valves will eventually stick if they are not periodically cycled.
3. If any if the hoses, pipes, fittings going in and out of the accumulator fail‐ the damper will lose all force capability within 1‐2 cycles. If these same hoses and fittings leak, the damper will lose all capability over time‐ and once the accumulator itself has expanded to its internal limit, an air bubble will be in the damper‐ causing loss of capability.

4. If the accumulator is sealed‐ with a nitrogen charge, then it will require periodic recharging from the gas slowly leaking around‐ and often through the rubber O‐ring seals that hold the gas in. If the accumulator is really cheap‐ it is not sealed, and just uses a simple coil spring to hold force on the accumulator piston. This design usually rusts the piston in place and the damper will catastrophically fail when cycled even once. Other accumulator types use gas bags‐ and over time the gas leaks right through the rubber of the bag. With gas bag accumulators, it is not uncommon to replace the gas bag every 5 years on critical use items‐ like a seismic damper.
5. If the accumulator is used for leakage make‐up, then it requires the periodic replacement of fluid plus a gas recharge. This requires very exact addition of fluid until the accumulator piston is typically in the centered position when the damper is centered‐ you pump in fluid until the piston is centered‐ requiring a special probe rod inserted into the accumulator cylinder. Then you recharge the gas. If the accumulator uses a gas bag instead of a piston then you have to open a bleed valve to remove fluid while pressurizing the gas bag. After the bag is at preload pressure with the accumulator empty, then you have to pump in a specified amount of fluid and close all fluid fill plugs.
Regards

Michael C. Constantinou
Professor, Department of Civil, Structural and Environmental Engineering (www.csee.buffalo.edu) Director, Structural
Engineering and Earthquake Simulation Laboratory (www.nees.buffalo.edu)
132 Ketter Hall
2
University at Buffalo
Buffalo, NY 14260
Ph: 716‐645‐2469