David Mrofka wrote:
> Surprise, we are having problems with our acid pump attached to a Delta V. 

Yeh, sounds familiar...

Check the following:

(1) Our main problem with the slipping belt was not caused by a blocked 
pump head or by low tension of the rubber belt (check both). The problem 
was the connection between the wheel and the shaft/spindle of the pump 
head. Contrary to first glance, the wooden wheel is not directly 
attached to the pump head drive. Remove the rubber belt, then remove the 
allen set screw which keeps the white ring in place (the PTFE ring with 
the nose which hits the trigger). This screw only fastens the white ring 
for the trigger and does not connect the wooden wheel to the shaft which 
moves the pump head (mark the position of the ring on the shaft before 
removing the screw).

There is a second allen set screw bellow the white ring which can be 
reached after moving the ring down. This set screw fixes the bushing 
(with the wheel) to the shaft which turns the pump head and needs to be 
fixed from time to time. In case this screw is loose it (a) either looks 
like the pump is running (wheels are turning) but the pump head does not 
move (you can see this if you look in the small slit under the pump 
between the case and the flow control ring). Or (b) the pump head is 
constantly "blocked" by the viscous H3PO4 because the power transmission 
between the wheel and the pump head does not work properly. In this case 
  the wheel seems to run "irregular". Sometimes it works, especially 
after stopping, but stops again after a few turns.

(2) Check the needle itself. Sometimes it is blocked with a piece of 
septum. We connected compressed air to the end and pressed the acid 
through (takes a few minutes). Put the tip of the needle in glass of 
water to see the progress. After the removal of the acid we flushed the 
capillary and needle with water (you can put the "pump end" of the 
capillary into a vial closed with a septum; fed a syringe needle through 
the septum which in turn is connected to compressed air).

In case this does not help let me know. There are some more things to check.

> Has anyone ever attempted to replace the wooden wheels and rubber belt with
> anything different...like a set of cogs and small chain?

Not a good idea, although I thought about that. The "slipping" is 
necessary in the case you create overpressure in the pump head (e.g. 
blocked needle). However, it is serious annoying in case of an untighten 
  screw.

regards,
Robert

-- 
Dr. Robert van Geldern
Section 3: Geochronology and Isotope Hydrology
Leibniz Institute for Applied Geosciences (GGA-Institute)

GEOZENTRUM HANNOVER
Stilleweg 2
30655 Hannover, Germany

mailto:[log in to unmask]