Test gags

The test gag is intended to block the opening of the valve while a hydraulic test on the system is performed. It physically blocks the spindle from moving upwards, preventing the valve from opening. 

Some manufacturers supply valves standard with test gags while for others it is an option, which adds to the confusion. Always check that the gag is removed before installing the valve, or the system could be endangered due to this simple but hazardous little device. 

First of all it is important to know that you should never work on a valve or make any adjustments when there is pressure under the valve disc. The forces, noise, and so forth, that could occur if a valve opened (especially on gas and steam) are life threatening. Remember to always purge the system before you start working on an SRV. Only if absolutely necessary use a test gag (Figure 10.1). 

Test gag Remove test gag. Sometimes test gags are incorrectly used to protect valve during transport or during hydraulic testing and often their removal is forgotten. 

Despite these theoretical concerns, a number of HIV vaccines are under development. Most of these vaccines have been developed by recombinant DNA techniques that have allowed a large-scale production of individual viral proteins. The predominant HIV proteins that make up these potential vaccines are env proteins (e.g., gp 120) and, to a lesser extent, gag proteins. In addition, inactivated whole HIV virus is being tested. 

The Berry spot test provides a rapid qualitative evaluation of urine. GAGs react with toluidine blue, a cationic dye, to yield a pink-colored compound. Alternative spot tests have been published but suffer from the same drawbacks regarding false-negative and false-positive specimens [2, 10, 15, 34]. Nevertheless, this fast procedure may pick up patients who have been referred to a laboratory for other metabolic examinations. For specific, initial MPS testing, the 1,9-dimethylene blue (DMB) assay, described below, is recommended. 

A first line-screening assay for MPSs is useful to evaluate the possibility of an MPS and to avoid tedious and expensive further laboratory testing of patients. The spot test described above can be used for a more general screening, for example when organic acids are requested from urine. However, GAG excretion is related to age, and... 

Fig. 4.1.5 Examples of a positive (a) and a negative (b) Berry spot test from urine. The filter paper will remain light blue after washing. The pink spot is typical for elevated glycosaminoglycan (GAG) excretion...

It is also recommended that the valve be isolated or gagged during pressure testing of the system, but make sure the gag is removed after testing. 

Compound CAS Registry Number LD50> gAg Test animal Reference... 

The biological oxidation rate of sulfur foam depends on available surface area, temperature) and access of necessary nutrients, as well as on foam composition. Preliminary test data indicate that in all cases the oxidation rate is less than that of elemental sulfur. Soil pH around the foams at Dempster Highway measured two years after installation was never lower than the pH of the surrounding native soil (Figure 3). Sulfur foam s low toxicity is indicated by the LD60 of > 5 gAg (rat) and the 100% survival rate in a fish bioassay with stickleback (96 hr) (8). 

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