Valve standard block

Thim · Feb 5, 2009

Hello,

Had a question about a standard Valve blocks controlled by 5/2 or 3/2 ventil.

If you would write one what functions would you want/need in that block.
Can think of a few,

Simulation Mode: Valve continues to work in program but in real life it is out of service.

Monitoring on/off: Check the position contacts yes or no

Hand/auto mode: explains it self

Keep track of total amount of changing position.

Monostabil/bistabil controlling

Status: - Alarm
- Auto closed-open
- Hand closed-open

Do you people have more sugestions? If yes would you like to specify them a little?

Thx

PeterW · Feb 5, 2009

In blocks that I've written in the past have included travel time-out for failed to open or close, also depending on the type of valve can monitor position and force back if it goes off position.

Failsafe positions if required.

Have had different blocks for spring return or double actuators, normally open/normally closed.

widelto · Feb 6, 2009

I designed an AOI ( add on instruction) for valves this way:
- command data: auto, man, man open man close, reset. (0-4)
- feedback, open and close (limit or prox switches)
- one timer, wait to close and open
- alarm, fail to open fail to close timer/done bit set
- color, green, red, green bliking, red blinking ( open ok, close ok, failed to open, failed to close respectively)

Thim · Feb 6, 2009

Thx both for the input lets see what others have as sugestions

Ken Moore · Feb 6, 2009

Well....
In the DCS I mantain, valve control blocks also have:
Interlock bit:
Interlock action, open/close
pulse outputs for latching controllers.
Ignore limit switches, but still function
disable bit

Hope this helps

seppoalanen · Feb 7, 2009

http://www.plctalk.net/qanda/attachment.php?attachmentid=9471&stc=1&d=1233993306

1. In Auto-Mode Closing if AUTO_OPEN is FALSE. AUTO_CLOSE is master if both are TRUE.
2. Auto/Man Mode selction from HMI COMMAND-WORD (Instance Property)
3. Manual control from HMI (Instance Property)
4. Jam control/UNKNOWN Position control.
5. Auto Disable Property
6. Jam discrite alarms for local OP-Panel/Scada if used
7. STATUS-WORD for HMI, includes alarms also if needed in HMI

I hope this help
- Seppo

jamesau · Feb 7, 2009

Devices of this sort typically have:

Field Inputs:
Feedback1: Closed / Not Closed
Feedback2(Optional): Open / Not Open

Other Inputs:
Mode: Auto / Manual
Auto Command: Open / Close
Manual Command: Open / Close
Interlock: OK / Not OK
Interlock Override (Optional - discouraged): Override / Not Override

Field Outputs:
Output: Open / Close

States (Derived from inputs/timer):
Closed
Open
Travel
Not Closed (alarm state)
Not Open (alarm state)
Interlock (alarm state)

Typically,
Auto Command is issued by sequences.
Manual Command issued by HMI but tracks Auto command when mode is Auto (bumpless transfer)

Thim · Feb 7, 2009

Thx for the input all of you.
Just some question for Jamesau and Ken Moore, What do you mean by interlock override not override?
Interlock like i know it are the conditions when a valve has to be openend/closed? If you override them isn't this the same like Manual Mode?
If you people mean interlock ok/not Ok, do you mean that your blocks have a bit saying the the valve has to openen/close? So if you question why the valve is not openning or closing you can check by that bit if all conditions are ok?

jamesau · Feb 7, 2009

Thim said:
Thx for the input all of you.
Just some question for Jamesau and Ken Moore, What do you mean by interlock override not override?
Interlock like i know it are the conditions when a valve has to be openend/closed? If you override them isn't this the same like Manual Mode?
If you people mean interlock ok/not Ok, do you mean that your blocks have a bit saying the the valve has to openen/close? So if you question why the valve is not openning or closing you can check by that bit if all conditions are ok?

An example:
A fail-closed tank-fill valve. The valve is to be interlocked with High High tank level alarm and tank rupture disk alarm. If either alarm condition is present while the valve is commanded open (regardless of mode), the valve's output will deenergize and an 'interlocked' alarm will be generated for the valve. The interlock override is generally a password protected feature, that when activated, would allow the valve to open in the presence of the above level or rupture disk alarms.

Thim · Feb 7, 2009

jamesau said:
An example:
A fail-closed tank-fill valve. The valve is to be interlocked with High High tank level alarm and tank rupture disk alarm. If either alarm condition is present while the valve is commanded open (regardless of mode), the valve's output will deenergize and an 'interlocked' alarm will be generated for the valve. The interlock override is generally a password protected feature, that when activated, would allow the valve to open in the presence of the above level or rupture disk alarms.

Ok, If i understood this well you give the valve some interlocks to close/open that can't be override by manual mode when this interlocks are high? Can i see it as extra safety? But you do have a possibility to open it when you know the interlock password?
Thx

jamesau · Feb 7, 2009

Thim said:
Ok, If i understood this well you give the valve some interlocks to close/open that can't be override by manual mode when this interlocks are high? Can i see it as extra safety? But you do have a possibility to open it when you know the interlock password?
Thx

Interlocks as I've illustrated provide a layer of safety; they're meant to protect personnel / property and should not be easily circumvented.

Valve standard block

Thim

Member

PeterW

Member

widelto

Member

Thim

Member

Ken Moore

Lifetime Supporting Member

seppoalanen

Member

jamesau

Lifetime Supporting Member

Thim

Member

jamesau

Lifetime Supporting Member

Thim

Member

jamesau

Lifetime Supporting Member

Similar Topics