Tech note #004

Mawenzi Laboratory

During my second month in Tanzania I am working full time at Mawenzi Regional Hospital in the centre of Moshi, repairing equipment. In the first week and a half my colleague Jaya and I have repaired six pieces of equipment in the laboratory, and a few elsewhere. In the course of this we also made a surreal organic discovery in the case of a sample incubator…

The entrance to the laboratory at Mawenzi Regional Hospital
The entrance to the laboratory at Mawenzi Regional Hospital

Mawenzi is a government hospital with about 250 beds. Most of the equipment is concentrated in two buildings: the laboratory and the surgery department. There are some high end machines in the imaging department, but we’re in no way qualified to work on these and they’re maintained by a group of technicians from Dar es Salaam trained in the US. The wards each have a blood pressure cuff, some stethoscopes, sometimes a pulse oximeter and not a lot else.

Overview of the main laboratory room
Overview of the main laboratory room

The laboratory at Mawenzi is one of the nicest buildings I’ve seen during my time here. It was built in 2011 and is alarmed, climate controlled, has emergency power and top end computerised analysis machines. Even more encouragingly, even though almost all the equipment was donated, many of the donors also donated service contracts. This is a really good example of how to make effective equipment donations: there’s an isolation chamber for testing of infection samples which needs new filters that cost $4000. With the service contract Mawenzi are able to order these and have them installed on time.

Donor plaque for the laboratory
Donor plaque for the laboratory

Though the building is new and most of the high end equipment is new, the same can’t be said for the more basic machines. Jaya and I have started a compendium of equipment-from-countries-that-don’t-exist-anymore: so far we have Czechoslovakia and West Germany. We’re confident we can get USSR and maybe Yugoslavia by the end of the month.

Equipment-from-countries-that-don't-exist-anymore West Germany Edition
Equipment-from-countries-that-don’t-exist-anymore Western Germany Edition
Equipment-from-countries-that-don't-exist-anymore Czechoslovakia Edition
Equipment-from-countries-that-don’t-exist-anymore Czechoslovakia Edition

Centrifuge

The first fix we made was one of the simplest and with the biggest impact. We were asked to take a look at two centrifuges, used to spin blood and other samples to separate suspensions into constituent parts.

I’ve been told of a mythical time when each bench in the laboratory had a centrifuge but as of me joining one had broken down about a year ago and another has been broken so long no one could personally remember it working. Only one was functioning.

Jaya with the two broken centrifuges, photographing Czechoslovakian glassware
Jaya with the two broken centrifuges, photographing Czechoslovakian glassware

We began by taking a look at the newer one thinking it was more promising, but when we opened the case someone had removed the motherboard. Our detective work has revealed that Mr. Abisai, the biomedical engineer at Mawenzi, removed it to try out something or other. He says he can get it back but there’s nothing we can do without it.

The second centrifuge is a much older model. It dates back to at least 1990, the year all centrifuges were required to have a mechanism to lock the lid during operation, which this machine doesn’t have. We rewired two loose connections in the plug and it fired up. The machine had sat untouched for many years due to a miswired plug.

The repaired centrifuge back in action in the lab
The repaired centrifuge back in action in the lab

We did also have to replace the dial and fix the faceplate up a bit, but this case is illustrative of how little basic technical expertise there is at Mawenzi. No specialist knowledge is needed to rewire a plug and you don’t need to fly engineering students out to do it. This wasn’t an engineering failure so much a systematic failure to perform basic troubleshooting before condemning a piece of equipment to the scrap heap. It just isn’t anyone’s job.

Distiller

A distiller in the lab was leaking, and it took a bit of discovery to work out why. This was an annoying machine to repair because to test it you have to turn it on, making the room extremely humid! Eventually we established the leak wasn’t a water leak at all, but a steam leak inside the case which was condensing. Unkinking the seal was enough to stop this happening.

The leaky distiller with the case removed
The leaky distiller with the case removed

We also discovered there is a voltage of over 20V from the machine case to ground, indicating a short to the case somewhere. In theory someone could touch the case and get a shock, which could hurt a little bit, so when we have more time we’ll get round to fitting a properly grounded plug.

Lab oven

Another very old piece of equipment in the lab is an oven used to heat samples. It was being kept in one of the small rooms, and the oven door couldn’t close. This meant the room got very warm and couldn’t really be used for anything else. A look at the sealing surface makes the problem pretty clear.

The laboratory oven with the door open
The laboratory oven with the door open

The entire front panel is rusted through in places with a lot of paint missing and it had bubbled up. We removed most of the external rust and smoothed the sealing surfaces with sandpaper. This was enough to allow the door to close and seal ok. The oven can now run on about half the power and the room is much cooler as a result. We discussed replacing or covering over the front panel, but for the staff it wasn’t a priority. We might get round to it later.

The lab oven with the door closed after improvements
The lab oven with the door closed after improvements

This is a good example of a broken piece of equipment having knock on consequences. Since we worked on the oven the staff in the lab now have two new work benches and a whole room they can use for other activities, where before it was only for storage and the oven.

Incubator

One of the more challenging projects we have worked on is a laboratory incubator. While there are ovens for heating stuff a lot, sometimes samples need to be kept at a specific temperature and for that an incubator is used. The incubator at Mawenzi couldn’t hold temperature very well, varying by up to six degrees.

Front view of the incubator
Front view of the incubator

We talked to the lab staff and determined that actually a small range is ok: most samples need to be held between 36° and 37.5°. In fact, a bit below 36° is ok, even down to 34° for short periods. Over temperature is another story though: 38° will begin to kill the samples.

This is a really old piece of kit, which we know because it’s the West German model, and so the temperature control is completely mechanical. The mechanism is actually pretty neat.

Inside the machine there is a glass vial with two metal contacts at one end. Inside the vial is a small pool of mercury and the whole thing is mounted on a gable so that it can tilt. A small element expands proportional to the temperature inside the incubator and tilts the vial so that the mercury flows to one end or the other. When the incubator is below temperature the mercury flows to the end with the connections, completes the circuit and turns the heater on. This expands the element until the mercury tilts back. When calibrated the mercury rocks backwards and forwards, keeping the incubator at the right temperature.

Mercury tilt senor
Mercury tilt senor

To improve the incubator was a simple matter of lubricating the mechanism and calibrating it so that it never goes over the temperature set on the dial. 80% of the repair was working out what was happening in the first place and how the calibration worked, and it now has a range of about 2.5°.

In working on this machine we made a pretty ridiculous discovery inside the case. Upon opening it up we found the usual minor bug infestation that is common to most machines, but also something new.

Standard issue bug stuff
Standard issue bug stuff

Resting on the insulation were a bunch of what I took to be small polystyrene balls.

“Small polystyrene balls”

Inevitably they weren’t polystyrene balls, but dozens of tiny lizard eggs.

Dozen of eggshells from the incubator casing
Dozen of eggshells from the incubator casing

We found an intact one, complete with lizard embryo.

Tiny lizard embryo (click to expand)
Tiny lizard embryo (click to expand)

Refrigerator

The final fix of our time in the lab was a refrigerator. The conversation went something like this:

Our refrigerator is supposed to hold between 2° and 8° but it hovers around -15° instead

Ok, let me take a look

*looks*

Ah yes, here’s your problem, you have it set on super mode

Super mode
Super mode

The eyewash station sums up our response.

P1000317

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