Ditch Witch FM25 - Manual (Page 43)

Drilling Fluid Concepts - 42
FM25 Operator’s Manual
Drilling Fluid Requirements
CMW
Drilling Fluid Requirements
1. Determine drilling conditions and choose appropriate drilling fluid mix.
2. Estimate amount of supplies needed and check availability.
• Drilling fluid
• Water supply. If more water than can be carried with the unit will be needed, arrange to transport
additional water.
• Bentonite and/or polymer
3. Check water quality.
• Use meter or pH test strips to test pH of water. If pH is below 9.0, add 1 lb (454 g) soda ash per
tank. Test and repeat until pH is between 9 and 10.
• Check water hardness using hardness test strips. Treat with soda ash if hardness exceeds 125
ppm.
Funnel Viscosity
Viscosity is the measure of internal resistance of a fluid to flow; the greater the resistance, the higher the
viscosity. Viscosity of drilling fluids must be controlled.
To determine viscosity, you will need a Marsh funnel (p/n 259-267) and a measuring cup, available from
your Ditch Witch dealer.
1. Using wash hose and a clean container, take a fresh
sample of drilling fluid. The sample must be at least
1.5 qt (1.4 L).
2. With finger over bottom of funnel, fill with fluid from
the container through the screen until fluid reaches
the bottom of the screen.
3. Move funnel over 1 qt (.95 L) container.
4. Remove finger from bottom of funnel and use the
stopwatch to count the number of seconds it takes for
1 qt (.95 L) of fluid to pass through the funnel. The
number of seconds is the viscosity.
5. Thoroughly rinse measuring cup and Marsh funnel.
IMPORTANT: Make sure Marsh funnel is clean and free of obstruction and that you have a stopwatch
available for timing the viscosity.