geofilter™ Flatstock Filter Membranes

For trace metals analysis in water, geofilter™ Flatstock Filter Membranes are designed to be used with the Geotech inline filter holders.

Features
Applications
Specifications
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Excellent reputation in the environmental industry since 1978
Wide variety of diameters and pore sizes available
Strong, flexible and economically priced
Resistant to variable temperatures
Compatible with Geotech In-Line Filter Holders
Pre-filters available for high turbidity applications

Cellulose Acetate Membrane: Recommended for most analytical filtration applications. Made of cellulose triacetate and diacetate, they are highly flexible with a high burst (longitudinal) and tensile (lateral) design strength. These membranes have the lowest extractable level at 0.1% (by wt.), improved heat resistance, low protein binding, and are resistant to low molecular weight alcohols.

Cellulose Nitrate Membrane: May be used in most Cellulose Acetate applications (see compatibility chart). Made of pure Cellulose Nitrate, they are typically 80% porous, allowing for excellent flow rates. They have a slightly higher extractable level at 3% (by wt.) and are composed of glycerin and wetting agent. As with all Geotech filter membranes, they are Triton-free and non-reactive to pyrogens (<0.005ng/cm² filter area).

PTFE Membrane: Are highly porous and resistant to most acids, bases and chemically aggressive solvents. They are naturally hydrophobic making them difficult to use in common filtration of aqueous solutions. They must be pre-wetted with methanol, acetone, or a compatible fluid having a low viscosity (<0.6 centipoise).

Glass Fiber Pre-filters: Are highly recommended for sediment laden samples to reduce the particulate loading on the membrane surface. A pre-filter will greatly extend the life of the membrane. The pre-filters are made by compacting borosilicate glass to form a dense fiber matrix. They are exceptionally pure, containing no binder that could alter the filtrate. Polycarbonate membranes are also available in a variety of pore sizes.

Cellulose Acetate Membrane

Pore Size¹² μm	Bubble Point¹ μm kg⁄cm²	PSI	Bar	Flow Rate: Water²	Air³	Porosity⁴	Thickness⁵	Weight⁶	Density⁷	Wetting⁸	Rf⁹	Max.¹⁰ Operating Temp.	Min.¹¹ Burst Pressure
0.8 WP	1.0	14.20	.97	160	13.5	72	125	4.7	0.39	<3	1.47	180	>1.0
0.45 WP	2.6	37	2.55	35	4.0	67	125	5.5	0.44	<3	1.47	180	>2.0
0.2 WP	3.3	47	3.24	16	1.9	66	125	5.8	0.46	<3	1.47	180	>2.0

Cellulose Nitrate Membrane

5.0 WP	0.75	11	.76	400	40.9	84	160	4.2	0.26	<3	1.5	130	<0.45
3.0 WP	0.90	13	.9	300	28.3	83	155	4.4	0.29	<3	1.5	130	<0.50
1.2 WP	1.15	16	1.1	220	20.4	83	150	4.4	0.29	<3	1.5	130	<0.60
0.8 WP	1.35	19	1.3	165	15.0	81	150	4.6	0.31	<3	1.5	130	<0.65
0.8 WG	1.10	16	1.1	145	13.9	78	135	4.9	0.36	<3	1.5	130	<0.50
0.65 WP	1.70	24	1.65	120	11.2	81	150	4.8	0.32	<3	1.5	130	<0.70
0.65 WG	1.30	18.5	1.27	100	10.2	76	135	5.0	0.36	<3	1.5	130	<0.60
0.45 WP	2.80	40	2.76	45	5.0	78	145	5.2	0.36	<3	1.5	130	<1.10
0.45 WG	1.85	26	1.79	57	5.8	77	133	5.2	0.39	<3	1.5	130	<0.80
0.3 WP	3.30	47	3.24	30	3.7	77	140	5.3	0.38	<3	1.5	130	<0.70
0.2 WP	4.30	61	4.2	17.5	2.4	75	133	5.5	0.41	<3	1.5	130	<1.10
0.1 WP	3.10	41	2.8	2.7	0.67	66	110	6.3	0.56	<3	1.5	130	<1.45

1 Bubble point is the minimum pressure in kg/cm² or psi required to force air through a membrane.
    Pre-wet with water except 0.1 micron pore size cellulose nitrate which is pre-wet with isopropanol.
2 Liquid flow rates reflect initial flow rates in ml/min/cm² using water prefiltered to 0.1 μm pore size at
    10 psi (.7 bar) differential pressure.
3   Air flow rates reflect initial flow rates of pre-filtered nitrogen in l/min/cm² at 10 psi (.7 bar) differential
     pressure.
4   Porosity refers to the percent of open area.
5   Thickness in μm.
6   Weight in mg/cm².
7   Density in g/cm²8   Wetting time is the maximum time in seconds to wet a 47mm diameter disc with aqueous 1%
     methylene blue.
9   Rf refractive index.
10 Maximum operating temperature in °C.
11 Burst pressure is the minimum pressure in kg/cm² required to rupture exactly 1 cm² area of dry
     unsupported membrane.
12 W = White, P = Plain, G = Grid.

Glass Fiber Pre-Filters

					Particle Retention
Order No.	Applications/Characteristics	Weight (g/m²)	Thickness (mm)	Liquid (μm)	Water Flowrate (sec)	Gas Max. Collection Efficiency	Pressure Drop mm/H₂O/ 5cm/sec	Binder	Max. Temp. °C
GGF-24	Used for course or general purpose pre-filtration.	123	0.52	2.7	14	97	25	None	500
GGF-28	Recommended for high volume filter holders. Has very low trace metal content.	95	0.38	2.0	18	9.9	32	None	500
GGF-30	Recommended for suspended solids analysis of industrial waters and waste waters. Low absorption makes this filter ideal for scintillation counting.	48	0.19	1.2	27	99.9	49	None	500

1 Water flow rates are the time required for filtering 1 litre of deionized water at 20°C through a filter
area of 9.6 cm² using 300 mm Hg vacuum.
2 Tests performed are conducted in accordance with ASTM D2986-71.

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