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Screwing the Screw Pump

By Prakash Subbarao

This afternoon I googled the words "Screw Pump" and Google returned 59,700 pages for that term. There were even three image results, one of which is featured above.

Why this sudden fascination for screw pumps? Well.........it's because I just took a trip down memory lane and remembered that my college project was to design and fabricate a screw pump. We carried out the task commendably and got very high marks; amongst the highest in the university, if I remember correctly. "What if we had screwed it up?" I idly wondered to myself. In doing so a beautiful story fell into place and it is this story that you read below.

There were five of us on this 10th Semester project team.

That year, for reasons unknown, the projects being handed out were exotic ones. I remember the four of us had dismayed expressions on our faces when we heard that our project was to be a screw pump. None of us had even realized until that moment that such a pump existed!

Back then, in the 1974, there was no internet and no Google. There were no vast online databases and the definitive word on any subject came from books in our college library.

"Do you have any books on Screw Pumps" we asked the librarian. I recall that the librarian was an elderly lady. She gave us a long stare to check whether we were trying to act funny with her and when she realized that we probably weren't, she checked her index. "No, there are no books on  screw pumps in this library" she declared with an air of finality.

Our next halt was at the library of the Institution of Engineers. No luck there either.

Someone proposed that we visit the Indian Institute of Science library and we all agreed that it was a terrific idea but we never got around to it.

Tenth semester was our last semester. Almost all of us were very busy applying for jobs and applying to US Universities. Hardly anyone was studying; this was a task best put off till the very end. One studied day and night during the holidays just before the exams.

One fine day, we were sitting in the canteen sipping a cup of coffee when someone mentioned the screw pump project. God! We had completely forgotten about it!

We were supposed to have a Professor who would guide us through this project but the guide was probably as much in the dark as to what a screw pump was as we were. A moment's reflection told us that we could not approach the guide at this late stage; we would be the objects of ridicule.

"Let's approach G.S. Ramesh and see whether he can think up something" someone suggested. G.S. Ramesh was a classmate of ours; he was a very studious bloke who looked forward to people going to him with technical problems. We were sure that he would help.

When we approached Ramesh he appeared definitely interested and enthusiastic. "Try the text books with Russian authors" he suggested. "You should definitely get a book on screw pumps and then we can take it from there".

We scoured every book seller in Avenue Road looking for a book on screw pumps. No luck. There were no books on screw pumps.

By now the word had spread all over the college that we were floundering.

A few days later a kindly professor approached us. He had recently joined the college and he wanted to help. "I heard you guys are looking for information on screw pumps" he said. "I was at Higginbotham's yesterday and happened to see a book on screw pumps there. Why don't you buy that book and get started?"

This news was Godsend. We raced to Higginbotham's and purchased the book. We then rushed to Ramesh and thrust the book in his hand. "Please go through this book and tell us how to get started" we pleaded with him.

A few days later Ramesh gave us the best news we had heard so far. "I have created a basic design for a screw pump" he said. "Show it to your guide and you can refine it further after getting his inputs".

If our guide was surprised at our sudden progress he didn't show it. He took a few days to study the design and then gave it his approval. All that was now left for us to do was to fabricate the damn thing.

Flushed with a sense of impending success we rushed to the college foundry. "We would like to make a core for the screw pump casting" we told the foreman. "That isn't possible" he coolly replied. "The foundry has already closed and will remain so till the end of this semester. Go to J.C. Road and find a pattern maker. He will help you make the core as well as the casting".

Our visit to J.C. Road revealed that the pattern makers there had never heard of a screw pump. They were so centrifugal-pump savvy that they could make one with their eyes closed but a screw pump was out of their league. Dejected, we sat sipping a cup of coffee at Kamat Restaurant when someone in the group (I don't remember who) had a brainwave.

"Why not just buy a second hand pump in the market and pass it off as a screw pump? Who will know the difference?"

There was a moment of stunned silence. "But the moment the examiner opens the pump he will know that it is not a screw pump" someone remarked.

"So let's have it so tightly sealed that the examiner cannot open it" someone else piped in.

"Let's go the gujry (second hand market) and see if we can get a pump" someone else excitedly interjected.

Soon we had a very rusty looking centrifugal pump in our possession.

"I can have it cleaned up at my factory" one of the team members said.

Ten days later the pump looked spanking new. It had been machined. The rust had been removed. It had been sand blasted and given a nice coating of paint. More importantly it had been sealed so effectively that it couldn't be opened. (We all tried our best to open it up. It gave us great satisfaction to fail in doing so).

A week before the exams the pump and the design had been submitted to the college authorities.

On the day of the exam all of us were very nervous. The examiner would be an external one from another college. The viva voce (orals) carried 25 marks and would be about the design aspects. The pump itself (design aspects, technology, fabrication quality etc.) would carry 75 marks.

We all passed the orals with flying colors. We had memorized Ramesh's design till we could recite it in our sleep.

"Open the pump" the external examiner told the attender.

We stood there, our hearts racing, as the attender tried to open the pump casing. "It is not opening, Sir" he told the external examiner.

Time was ticking by and the Examiner couldn't spend to much of time on one project.

"Are you sure that you have done the fabrication as per the drawing?" he asked, looking at us closely.

"Yes Sir!" we said in unison.

"OK, you may go" the Examiner said and we trooped out with broad smiles on our face.

We got 24 out of 25 in the viva and 74 out of 75 for the fabrication.

These marks were amongst the highest in the University, that year.

Did the above really happen?

Take a look at the screw pump in the image at the top of this page. A screw pump needs to be long and cannot be mistaken for a squat centrifugal pump.

Unless the Examiner is a complete dolt.

What do you think? Did this really happen?

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