- Compliance with DIN ISO 835 standard with colour code.
- Accuracy as per Class ‘A’. With individual certificate
- Printed in Amber/ Blue Colour
- These pipettes are graduated for delivery from zero mark to the last graduation mark
- Colour coded for each capacity making it easier to recognise
OVERVIEW :
The GWSI 25 ml Class A Mohr pipette is a measuring pipette that delivers between two marks — the scale stops above the jet. Premium borosilicate 3.3 glass gives high thermal shock resistance, hydrolytic resistance, and chemical inertness on a long 25 ml stem. Interval is 0.20 ml; Class A tolerance is ±0.10 ml to ISO 835 Type 1. Calibrated to deliver (TD) at 20 °C. Do not blow out. That last drop is not in the volume. Class B glassware is the teaching Mohr; this SKU is Class A volumetric glassware. Interchangeable ground joints stay on flasks.
HISTORY :
Karl Friedrich Mohr, working in mid-1800s volumetric analysis, needed a pipette that did not argue about the film in the tip. His measuring pipette put every delivered millilitre between two lines and left the jet out of the calculation. ISO 835 later called that Type 1. Serologicals went to the tip and added blow-out; Mohr stayed between the marks. GWSI Glass Lab still draws the 25 ml Class A Mohr in Ambala as autoclavable lab glass.
APPLICATIONS :
– Pharmaceutical labs: 25 ml QC takes where blow-out is not allowed
– Biotech: measured media and buffer aliquots between two lines
– Industrial laboratories: process checks at 0.20 ml steps, Class A error
– Research labs: quantitative transfers that must not include the jet
– Schools, colleges, universities & educational institutes: teaching Mohr vs serological technique
– Hospital and diagnostic benches: measured reagent make-up without a blow-out step
MANUFACTURING PROCESS :
GWSI melts high-purity borosilicate 3.3 and draws a 25 ml stem by master hand-blowing or automated tube-draw. The jet is formed, but the scale is laid out to stop above it — that dead volume is the Mohr design. The blank anneals on full-length supports so the long tube stays straight before the 0.20 ml scale goes on.
TESTING PROCESS :
First inspection is manual: jet, last graduation clear of the tip, 0.20 ml pitch, and straightness. A polarization stress test on the polariscope follows. Delivery is then checked to I.S.O. DIN (ISO 835 Type 1) on a manual or automatic stand — TD at 20 °C, **meniscus to meniscus, no blow-out**, Class A ±0.10 ml. NABL gravimetric calibration is available on this Class A piece; Class B Mohr lots use the wider table.
PRINTING PROCESS :
The 0.20 ml Mohr scale (zero at the top, last line above the jet), Class A / TD / 20 °C, colour code, and GWSI name are precision silk-screened with glass enamels (ceramic inks). Kiln heat drives ceramic glass fusing so the scale locks into the glass matrix and will not fade in detergent or steam.
PACKAGING PROCESS :
Cosmetic sorting pulls seeds, bent stems, and any scale that runs too close to the jet (that would be a serological). Pass pipettes pack in heavy-duty double-wall boxes with shock-absorbing bubble wrap, full length cradled, tips guarded, for export from the Science City.
MAINTENANCE & SAFETY :
– Never mouth-pipette — use a filler that can lift 25 ml
– Never blow out — if you empty the jet, you have over-delivered
– Set the upper meniscus, deliver to the lower mark; the tip stays wet
– Read at eye level; interval is 0.20 ml; work near 20 °C
– Do not use this as a serological; there are no blow-out rings
– Wash in a 25 ml-length pipette washer
– Autoclave this autoclavable lab glass at 121 °C only if the SOP allows; recheck Class A volume after heat
– Store full-length in a deep rack
– Retire any pipette with a chipped jet, a scale that has worn off the last line, or a bent stem