Laserfiche WebLink
3.0 INTERFERENCES <br /> 3.1 Potential interferences that may be encountered during analysis are <br /> discussed in the individual analytical methods. <br /> 4.0 APPARATUS AND MATERIALS <br /> 4.1 Agitation apparatus : The agitation apparatus must be capable of <br /> rotating the extraction vessel in an end-over-end fashion (see Figure 1) at <br /> 30 + 2 rpm. Suitable devices known to EPA are identified in Table 2. <br /> 4.2 Extraction Vessels <br /> 4.2.1 Zero-Headspace Extraction Vessel (ZHE) . This device is <br /> for use only when the waste is being tested for the mobility of volatile <br /> analytes (i .e. , those listed in Table 1) . The ZHE (depicted in Figure 2) <br /> allows for liquid/solid separation within the device, and effectively <br /> precludes headspace. This type of vessel allows for initial liquid/solid <br /> separation, extraction, and final extract filtration without opening the <br /> vessel (see Section 4.3.1) . The vessels shall have an internal volume of <br /> 500-600 mL, and be equipped to accommodate a 90-110 mm filter. The devices <br /> contain VITON®' 0-rings which should be replaced frequently. Suitable ZHE <br /> devices known to EPA are identified in Table 3. <br /> For the ZHE to be acceptable for use, the piston within the ZHE <br /> should be able to be moved with approximately 15 psi or less. If it takes <br /> more pressure to move the piston, the 0-rings in the device should be <br /> replaced. If this does not solve the problem, the ZHE is unacceptable for <br /> TCLP analyses and the manufacturer should be contacted. <br /> The ZHE should be checked for leaks after every extraction. If the <br /> device contains a built-in pressure gauge, pressurize the device to <br /> 50 psi , allow it to stand unattended for 1 hour, and recheck the pressure. <br /> If the device does not have a built-in pressure gauge, pressurize the <br /> device to 50 psi , submerge it in water, and check for the presence of air <br /> bubbles escaping from any of the fittings. If pressure is lost, check all <br /> fittings and inspect and replace 0-rings, if necessary. Retest the <br /> device. If leakage problems cannot be solved, the manufacturer should be <br /> contacted. <br /> Some ZHEs use gas pressure to actuate the ZHE piston, while others <br /> use mechanical pressure (see Table 3) . Whereas the volatiles procedure <br /> (see Section 7.3) refers to pounds per square inch (psi ) , for the <br /> mechanically actuated piston, the pressure applied is measured in <br /> torque-inch-pounds. Refer to the manufacturer's instructions as to the <br /> proper conversion. <br /> ' VITON® is a trademark of Du Pont. <br /> CD-ROM 1311- 2 Revision 0 <br /> July 1992 <br />