Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Compressor protection

Compressor protection

Compressor protection


This is with regard to the shutdown signals of a four stage Reciprocating COmpressor for process Air service (disc pressure of 32 barg). The compressor is of API618 compliance...As per table 5 of API 618, there are four signals that calls for shutdown of the equipment.

All the four signals ( Vibration, Lube oil pressure, Inter stage Separator moisture /water level and inter-stage air temp). The first two are already connected to ESD system where as the Inter stage separator level and air temp are presently connected to DCS system to initiate trip when these two parameters go for HiHi. We also have pre-alarm Hi for the above two signals.

The clarification here is whether these two signals are also to be connected to the ESD as a part of Equipment protection? It is argued that DCS system is not reliable as ESD. How shall we approach this ? IPF study has been conducted and it allowed these two signals to get connected to the DCS system but Client does not agree to this ....

Thanks to guide .

RE: Compressor protection

I am not instrument specialist, so just my two cents on it:
You did not specify what is the voting philosophy for shutdown (2oo3 ?) - and is it same for all of the four signals ?
If clients want these trips to be initiated by ESD then why not just do it and kill the subject?
Don´t know which type / stage of engineering you are in (concept design, execution, upgrade or modification of existing system...)... If IPF study says DCS is okay (BTW : Did the client approve the IPF study?), going for ESD would be then a bit of an "over-kill", but if clients wants so - where is the problem?
Point here is we talk just two signals, so cost and effort seem minor (unless you would have a dozen of machines across plant that are to follow same philosophy...).

RE: Compressor protection

It is a four stage unit, so there are 3 interstages, each with a temperature sensor and an interstage scrubber. All of the kills required by API 618 are quite independent from each other (e.g. a stuck third stage suction valve will give you a 3rd stage discharge high temp and an interstage trip without any vibration, with good lube oil pressure, and good temps in the other stages, should still shut the machine down. Whether you shut it down with the DCS or the ESD systems just depends on your process philosophy. All of the kills must be part of the safety systems and be subject to calibration and testing protocols.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


White Paper: Industrial Control Basics: Contactors
A contactor is an electrical device used for switching an electrical circuit on or off. Considered to be a special type of relay, contactors are used in applications with higher current carrying capacity, while relays are used for lower current applications. Download Now
Research Report: State of IoT Adoption in Product Development 2019
This research report, based on a survey of 234 product development professionals, examines the current state of Internet of Things (IoT) adoption by product design teams, its perceived importance, and what features and capabilities teams consider important when making decision about adding IoT functionality to their products. Download Now
Research Report: Augmented Reality for Maintenance, Repair and Overhaul (MRO)
The term Industry 4.0 denotes a cluster of technologies that’s poised to fundamentally reshape manufacturing and bring about a new industrial revolution. These include 3D printing (AM), the Industrial Internet of Things (IIoT), artificial intelligence (AI) and mixed reality technologies, more commonly known as virtual reality (VR) and augmented reality (AR). Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close