Charge Houses and Tanks
This is the first and non-explosive stage in the production of Nitroglycerine at the two Units in M/S Factory Dalbeattie.
The details are available thanks to the foresight of Mr. Gordon Nicholson who in 1941 to 1943 was the Acid Plant Manager
at Dalbeattie. His documents have permitted a reconstruction of the entire Nitration process and most aspects of the
Washing and Wash Water disposal processes that made the product safe to use.
The Charge Houses at Dalbeattie were structures that held some of the weather-sensitive ingredients of the process, the
huge tanks for acids and compressed air being durable enough to stand outside. The Control Blockhouse is referred to in
Nicholson's work as housing a safety system, but there are also references to control gauges and switches that were in
the Nitration House but may have been duplicated in the Blockhouse for safety reasons. The details are discussed on this
Processes at the Charge Houses and Tanks (after Gordon Nicholson) :
Mixed Acid (M/A or N/G-M/A) received in tankers from MS Factory Dumfries was pumped down 2" steel pipes some 1520 feet
long (approx. 500 metres) from tanks at the Acid Plant to 2 x 80-tonne tanks at the charge house beside the Nitration Hill.
From there, it was blown by low-pressure air along a 200 feet long pipe into the nitrator when required.
- Mixed acid (57% Concentrated Sulphuric Acid and 43% Concentrated Nitric Acid), was stored in mild steel horizontal tanks (boilers) of 160,000 lbs capacity near the Charge House.
- Glycerine was delivered by rail in drums of 560 to 1680 lbs net weight, then emptied into three steam heated tanks of
13.5 tonness capacity, from which it was piped to a pair of 5 tonne capacity steam heated tanks in the charge house.
- Wash liquids were stored in three boilers in the charge house : Hot water (8,300 litres), Cold water (9,800 litres) and
soda water (sodium carbonate solution) (8,300 litres).
- High pressure air at 75 lbs/square inch (2.5 atmospheres) was delivered to a 930 cubic feet storage vessel beside the charge house,
then reduced to about 28 lbs/square inch (0.9 atmospheres) low pressure air before being piped into a 100 cubic feet vessel
in the ground floor of the Nitration House. This low-pressure air was used to drive the mixed acid, glycerine and wash-water
solutions to where they were needed, and where necessary to aerate the mix.
- A small quantity of oil was added to the process of nitration to enhance (accelerate) separation of the nitroglycerine
from the mix of acids and glycerine following reaction.
The nitration process as a by-product produces a much weaker acid (Nitrogylcerine Refuse Acid or N/G-R/A) mix contaminated
with small amounts of nitroglycerine, water and other impurities. This 'Refuse Acid' was initially stored in tanks outside
the Nitration House embankment then pumped back to the Acid Plant for reprocessing.
Archaeological Evidence for the Charge House and Tanks :
- Unit 1 :
The Mixed Acid tank bases and the High Pressure Air Tank base are beyond Nitration Hill AB1 on its north side, so at some
distance from the one Blockhouse and the Charge House; what may be the walls of the Refuse Acid tank base is beside the
Blockhouse. Regrettably, the Charge House was demolished and its remains lie partially under thornbushes and partly as a
cleared area. It seems that the twin Nitration Houses shared a Blockhouse, which may explain its position almost between them. Malcolm Bowditch has
suggested that one Nitration House may have been shut for maintenance whilst the other was operating, which might make
sense and avoid duplication of controls. However, there is also a rectangular cleared area south of the Blockhouse that has
not been excavated but which would be large enough for a Charge House. The probable Charge House site can therefore only be
verified by excavation, as map data in this area is very unreliable.
- Unit 2 :
The Charge House, the presumed Blockhouse, the Mixed Acid Tank bases and High Pressure Air tank base survive, but with loss
of much detail. The Refuse Acid Tanks location could not be established and may have been demolished. Originally there
were two Nitration Hills, as in Unit 1, but only opne survives.
The Charge House in Unit 2, next to the Nitration House, is a rectangular brick building that once had a flat composition
roof on metal girders. The building is split by a wall, the smaller room being about half the width of the larger room
and with drainage channels in the floor. The walls have the remains of reinforced glass windows. Access to each room is
by doors in the outer wall; there is no door through the partition. In view of the known information, it is suspected that
the larger room housed the Glycerine and Soda tanks, possibly with the Hot and Cold Water tanks in the smaller room.
Alternatively, all the tanks may have been inside the larger room, the smaller room being for machinery such as pumps and
possibly the stand-by battery racks. The controls may have been in the larger room where tanks could be watched, or in the
There is a lot known about the Charge House, rather less about the other asociated features. Much of this supposition
can only be tested by reference to other sites and by excavation.
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