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  1. sjohnr

    I'm a subsea engineer with mechanic

    You should initially be discussing this with your potential subsea control system suppliers. Depending on the field size, i.e. tree count, distances, they can estimate the load on each line from which they can estimate a suitable electrical conductor size. They may also have a preference for...
  2. sjohnr

    Intrinsically Safe Pneumatic Equipment

    I used to be up on this but since moving to the US I'm a bit behind. I recently stumbled on an air driven motor, perfect for an application we're working on, but the manufacturer (I won't mention the name) claims that it is intrinsically safe! And quotes all sorts of convincing ATEX type...
  3. sjohnr

    Rotary Clicker Input Gadget Type Thing

    Thanks for your replies on this. Optical was the part I was missing. I've got some suitable part numbers now. The offset cam idea is something I need to remember. But as you suggest waross, the path of least resistance is just to buy the device. Thanks again.
  4. sjohnr

    Rotary Clicker Input Gadget Type Thing

    The Bosch ovens in Europe used to have a knob to turn that set the desired temperature. Their would be about 10 or 12 clicks per rotation. But the neat thing was that the electronics would increase the rate of change of the desired temperature according to how fast those clicks were coming in...
  5. sjohnr

    Subsea piping installation

    Generally, the same materials are used subsea as are used in surface applications, the main difference is in the external coating. You would need specialist advice on that. Additionally, some form of cathodic protection may be required, this is usually implemented using sacrifical anodes...
  6. sjohnr

    Using Fibre Optic to Switch a Voltage?

    nbucska, I really appreciate your concern over this but the information provided by others (and you) at the start of the thread was actually all I needed to start the design of the system. I think you should put your energy in to some other thread. Thanks anyway.
  7. sjohnr

    Using Fibre Optic to Switch a Voltage?

    For a control systems engineer the word remote does not mean 1 mm. Again, I am not asking anybody to design the system. We are doing that ourselves right now.
  8. sjohnr

    Using Fibre Optic to Switch a Voltage?

    I can't imagine any control systems engineer reading my question and believing that a piece of string would do the job. I've already stated the objective, low cost and high reliability, which we intended to achieve by keeping the system simple. Why only optical fiber? As I've said in the...
  9. sjohnr

    Using Fibre Optic to Switch a Voltage?

    Gents, Thanks to both of you for your good suggestions. Since the "communictaion" is one way, I am thinking of using an emitter and detector module at each end of the fibre. Although these seem to be designed for comms systems they are cheap. I just need to get hold of a data sheet and work...
  10. sjohnr

    Using Fibre Optic to Switch a Voltage?

    I have a slightly bizarre control problem. We have a solenoid operated hydraulic control valve at a remote location. The solenoid is operated by a 24 Vdc supply. There is a plentiful supply of 24 Vdc at the remote location but the only link to the remote location is by optical fiber, of...
  11. sjohnr

    Line integrity monitoring - SIS Design

    I thought the whole idea of a 4 to 20 mA loop is that an open circuit gives you 0 mA so you have built in open cct detection. If the broken wire grounds out the circuit will overrange. Either way the fault gets picked up. I must be missing something.
  12. sjohnr

    Non-Powered Liquid Level Switch

    Another one would be http://www.koboldusa.com Regards
  13. sjohnr

    Roughness value for rubber hose

    Any markings? Manufacturer? Part number?
  14. sjohnr

    Roughness value for rubber hose

    Is it really rubber hose or some type of plastic? I have used an absolute roughness figure of 0.7 micron in the past for hose having a liner extruded in nylon.
  15. sjohnr

    CONTAMINATION CODES

    The other two codes in common use are NAS 1638, an obsolescent code although still in use in some industries, and SAE 4059D. The first step is to identify those components in the system that are sensitive to particulate contamination, the manufacturer of those components should be able to tell...
  16. sjohnr

    WhatÆs the difference between pre-commissioning and commissioning?

    For starting up a process control system I am used to this routine: 1. Install the various subsystems. 2. Perform hook-up of the subsystems. 3. Post-installation testing of the subsystems: this is usually basic things like testing of connections for integrity and continuity, no functional...
  17. sjohnr

    Standards for connectors

    Costas, I'm assuming that you're talking about about relatively small bore hose, starting at 10 mm but no bigger than 30 mm. Connectors/couplings in this range are usually proprietary and subject to patent protection. There are no codes specific to self sealing quick couplings. If a...
  18. sjohnr

    Physical Properties Sea Water

    I've just been through this. For the denisty you need the UNESCO International Equation of State (IES 80) as described in Fofonoff, JGR, Vol 90 No. C2, pp 3332-3342, March 20, 1985. There are a few web sites that have Java calculators for it. Here's one...
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