×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

Discharge head

Discharge head

Discharge head

(OP)
Gentlemen, I should remember this from school but its been 30 years. I have a 3000 gpm centrifugal pump that the only way to get the head needed is to reduce flow. But this causes many thrust problems with broken shafts. Slowing down the speed of the motor will reduce flow but how much will it reduce discharge head.  

RE: Discharge head

Volume Capacity
q1 / q2 = (n1 / n2)       

Head or Pressure
dp1 / dp2 = (n1 / n2)^2       

Power
P1 / P2 = (n1 / n2)^3         

RE: Discharge head

(OP)
Answered the question.
Ship originally installed the 3000 gpm sea water pump with load of close to rated gpm. About a year later AC chiller condenser tube went so they change it to FW cooled. This left
SW pump with little load but close to shutoff head was still needed to cool another AC condenser very high up in the ship. So throttling to get discharge pressure caused shafts to break. 20 years later Port Engineer wants to put a variable speed drive controller on pump. I told him slowing down the pump wouldn't do the trick.  

RE: Discharge head

How will you "slow" the speed of the motor? If you are running a fixed speed motor the option will be to reduce the impeller diameter.

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!


Resources