Bio-Rad Model 785 Vacuum Blotter - Manual (Page 13)

Section 5
Troubleshooting Guide
5.1 Operational Troubleshooting
The following table summarizes possible Vacuum Blotter operational difficulties,
probable causes, and remedies. Refer to Sections 3 and 4 for recommended procedures.
Solutions/
Condition Probable Causes Preventions
1. Upper buffer level • No water-tight seal • Make sure that gasket
drops too fast during formed between O-ring covers the entire O-
run. and Window Gasket. ring before placing
the reservoir frame.
• Prewet O-ring with H2O.
• Incorrect window size • Refer to Section 3.2,
for the transferred gel. Step 2 on how to deter-
mine correct window
dimensions.
2. Gel does not attach • No vacuum in the • Check tubings, conn-
to window or float window area. ections, and regulator
during transfer. bleeder for vacuum leaks.
• Check vacuum pump by
placing finger at vacuum
port.
• Too low vacuum + • Maintain a constant
violent disturbance 5 inches Hg throughout
during transfer. the run. Minimize bench
disturbance.
• Incorrect window • Refer to Section 3.2,
dimensions for a gel. Step 2 on determination
of window dimensions.
3. Difficult to get acc- • Too strong vacuum • Bleed some pressure off
urate reading from pump used. by employing a three-way
the regulator gauge. valve.
• Violent shaking of • Stop the shaking or place
pump when placed near pump on another bench.
regulator.
• If using Bio-Rad pump. • Prewarm pump for 10
minutes before transfer.
4. Vacuum pressure • Pump was not pre- • Prewarm pump before
changes during run. warmed. transfer.
5. Moisture in regulator. • Liquid trap container is • Use a 1,500-2,000 ml
too small. side-arm flask
• Too much liquid in the • Remove liquids from the
trap. trap every run.
9