Product

Filter Funnels with Sintered Disc

OVERVIEW:
GWSI Filter Funnels with Sintered Disc are built from premium borosilicate 3.3 glass with a porous fritted disc fused straight into the stem. They filter without paper, so you get clean, particle-free filtrates from a reusable, chemically inert medium. High thermal shock resistance and strong hydrolytic resistance let them take hot solutions, aggressive solvents, and repeated autoclave cycles without cracking or leaching. Available with plain stems or interchangeable ground joints to lock onto any flask — the same build standard as GWSI’s Class A and Class B volumetric glassware.

HISTORY:
The sintered glass filter emerged from the Jena glassworks in the early 1900s and became a lab staple through Fritz Pregl’s Nobel-winning microanalysis work. It solved one simple problem: filtering hot, corrosive, or ultra-fine samples without paper fibers dissolving into the filtrate. The fused-glass disc replaced disposable paper with an inert, reusable filter that lasts for years.

APPLICATIONS:
– Pharmaceutical QC— clarifying reagents and filtering samples without fiber contamination.
– Biotech labs — sterile filtration of culture media, buffers, and protein solutions.
– Industrial laboratories — solvent cleanup, gravimetric analysis, and aggressive chemical filtration.
– Schools, colleges & universities— dependable glassware for chemistry practicals and gravimetry.
– Research labs & educational institutes — routine vacuum filtration where paper just won’t do.

 MANUFACTURING PROCESS:
GWSI melts high-purity borosilicate 3.3 tubing and rod, shapes each funnel by master hand-blowing or automated molding, fuses the sintered disc into the body by ceramic-glass fusing, and then anneals every piece to relieve all thermal stress.

TESTING PROCESS:
Every funnel passes a manual first inspection, then a polariscope polarization stress test to confirm zero residual stress, followed by ISO/DIN dimensional checks on manual or automatic testing machines, plus NABL gravimetric calibration on volumetric items.

PRINTING PROCESS:
Markings are applied by precision silk-screening with glass enamels (ceramic inks) and baked in high-temperature kilns to permanently fuse the scale into the glass matrix, so it never fades.

PACKAGING PROCESS:
Each piece undergoes cosmetic sorting to filter out blemishes, then ships in heavy-duty double-wall boxes with shock-absorbing bubble wrap for safe export.

MAINTENANCE & SAFETY:
– Rinse immediately after use, then back-flush with water and a mild detergent or lab cleaning solution.
– Never filter hydrofluoric acid or hot concentrated alkali — they etch glass.
– Autoclave at 121 °C; let pieces cool slowly to avoid thermal shock.
– Store dry, upright, and dust-free, with stems and joints protected.