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While many mistakes have been made with alcohol and tobacco policy over the past century propranolol 80mg with visa arteria meningea media, more appropriate and effective responses have now been developed buy discount propranolol 80mg pulse pressure and blood pressure, if not universally adopted buy propranolol with american express blood pressure chart 5 year old. It should be acknowledged that alcohol and tobacco’s unique historical purchase 40 mg propranolol amex iglesias heart attack, cultural and legal status—and their very distinct effects and patterns of use—do, to some extent, demand a degree of pragmatic realism and fex- ibility. However, even given this, there can be no good argument made for not developing alcohol and tobacco management policies based on the aims and working principles that drive this book’s thinking. The same menu of regulatory tools is available; the same policy outcomes are sought. It is therefore both consistent and necessary to combine moves toward effective legal regulation of currently illegal drugs with calls for improved regulation of currently legal drugs. Likewise, each seeks to achieve the widely shared goals of reducing personal and social harms associated with drug production, supply and use, and the broader promotion of health and wellbeing. There remains, however, one key difference between managing legal and illegal drugs. The alcohol and tobacco management improvement process has been able to ask, and to some degree answer, questions about which forms of regulation are most effective. These are ques- tions of vital importance; the current legal framework for most other drugs denies us the opportunity to explore them in the context of those drugs, and thus with the full depth and rigour that they both deserve and demand. A consistent approach to policy across all drugs will help reverse this research gap. It thus holds the prospect of dramatically improving not only policy around currently illegal drugs, but also alcohol and tobacco policy. Some of this research has been alluded to throughout this book; rather than revisit this well established analysis, this brief discussion will focus more on some of the wider themes that have emerged from it, and their implications for other drugs. This value is added to by the various beverages, and sometimes foods, with which it is mixed and consumed. Over and above this, many alcoholic beverages have them- selves assumed cultural roles and importance only tangentially related to their intoxicating effects. For example, they have been used in cooking, or as components of religious rituals. It is For alcohol policy to acknowledged that, for example with wine have an effective future connoisseurs, alcoholic beverages are not it is clear that potentially consumed exclusively for intoxication. With the possible exception of caffeine, alcohol is the most widely used non-medical psychoactive drug. The scale of alcohol use and its global cultural penetration help explain why its negative public health impact is only exceeded by tobacco. If there is any upside to this, it is that a wide spectrum of policy approaches to controlling alcohol have been experimented with, in widely varying social contexts, including unregulated free markets, various formulations of licensed sales, state monopolies, and prohi- bition. These experiments have taken place across the globe and 101 1 2 3 Introduction Five models for regulating drug supply The practical detail of regulation throughout recent history. Thus, in order to be effective, a comprehensive alcohol policy must not only incorporate measures to educate the public about the dangers of hazardous and harmful use of alcohol, or interventions that focus primarily on treating or punishing those who may be putting at risk their own or others’ health and safety, but also must put in place regu- latory and other environmental supports that promote the health of the population as a whole. This is advice that, with some necessary tweaks and variations, clearly describes the approach to drug policy and regulation being more widely advocated here. Indeed, it is often a revealing experience to read author- itative texts about alcohol control policy, changing the words ‘alcohol’ to 54 ‘drugs’, and ‘drinking’ to ‘drug use’. The fundamental confict between public health policy, and alcohol sale and consumption as a commercially driven activity, is a key issue, coming up repeatedly in alcohol policy literature. This issue raises a series of important concerns for the wider drug policy and law reform agenda. The production and sale of alcoholic beverages, together with the ancillary industries, are important 54 For a paired example see: ‘After the War on Drugs: Tools for the Debate’, Transform Drug Policy Foundation, page 16, 2006. These economic and fiscal interests are often an important determinant of policies that can be seen as barriers to public health initiatives. Dissemination of public health research that can counterbalance these economic and fiscal interests is paramount. Alcohol producers and suppliers see alcohol from a commer- cial rather than a public health perspective. They do not bear the secondary costs of problematic alcohol use; quite naturally, their primary motivation is to generate the highest possible profits. This is logically achieved by maximising consumption, both in total popula- tion and per capita terms. Public health issues become a concern only when they threaten to impact on the bottom line, and will invariably be secondary to profit maximisation. They have achieved this by deploying a now familiar menu of high level lobbying, manufactured outrage and populist posturing (the ‘nanny state’ against ‘a man’s right to have a drink after work’ etc. In many countries these efforts have been highly effective at distracting from, or delaying, any meaningful regulatory legislation. In addition, they have often successfully kept what regulation has been passed at a voluntary level, meaning that it can largely be ignored or sidelined to the point of being almost completely ineffectual. Yet this is exactly what is required to address particular issues of binge and problem drinking, and to support the general evolution of a more moderate and responsible drinking culture. It is important to remember that problem- atic and binge drinking constitute a signifcant proportion of alcohol industry profts; they are, quite simply, hugely proftable consumer behaviours. Such concerns have prompted adoption of government monopoly control models for sections of alcohol supply in some coun- 57 tries. Examples include the Systembolaget system in Sweden, under which the state controls all import and supply, and the provincial government control of alcohol off-licences in some Canadian prov- inces (Ontario and Quebec). These models have some similarities to the Regulated Market Model proposed for tobacco (see: page 27). These factors combine with the immense lobbying power of alcohol industry bodies, and the public unpopularity of restricting alcohol sales or increasing prices, to create massive political obstacles to effective reforms. This is the case even when knowledge of what works from a public health perspective (that is, encouraging reduced and/or moderate consumption) is clear. In effect, many governments have been complicit in the growing public health crisis associated with alcohol. For alcohol policy to have an effective future it is clear that poten- tially very unpopular decisions will have to be made that will involve increasing regulation and heavy restrictions on all aspects of marketing and promotions. How such reforms unfold, combined with historic successes and failures in alcohol control, will continue to provide a rich resource for future, legally regulated markets to learn from. It is, however, associated with a disproportionate level of health harms, on a scale that eclipses all other drugs combined. These huge public health impacts are predominantly associated with smoked 58 tobacco; they are related to its high propensity to produce dependency, alongside the fact that it does not intoxicate to a degree that signifcantly impairs functioning. Many smokers consume nicotine more than 20 times every day, for prolonged periods—commonly over many years. Despite the high risks smoking presents (around half of smokers will die prematurely as a result of their use) the low level of intoxication created by nicotine has not historically attracted the moral indigna- tion that fuelled the temperance movement and shaped much punitive prohibitionist thinking on other drugs. As such, tobacco has assumed a unique role in society; a highly visible pattern of dependent drug use associated with a high risk of chronic health harms, yet one that 58 It has a rapid onset, a short half life, is associated with development of tolerance and distinct withdrawal effects and cravings—on top of psychological effects related to habituation into various personal and cultural consumption rituals. The public health disaster associated with smoked tobacco has, however, ultimately led to the emergence of a range of more pragmatic public health and regulatory responses in a number of countries. Like alcohol, the full gamut of policy responses to tobacco can be observed and learnt from, and there is a substantial body of related scholarship to be drawn upon.
A generic Each section includes the following topics for medication may be made by many different the different medication types: manufacturers discount propranolol 80mg with visa heart attack recovery diet. Additionally order propranolol 40mg without a prescription blood pressure phobia, manufacturers Purpose: Describes typical uses of medica- can make several forms of a single medication tions order online propranolol blood pressure bottom number, including specifc symptoms treated and with only slight variations buy online propranolol blood pressure medication breastfeeding. For ease of reading, some technical terms are The section, “Talking with Clients about their 4 defned in accompanying footnotes. All Medication,” is a prompt designed to help the medications are listed in the index along with provider initiate conversation about medica- page numbers for quick reference. When tion management and adherence with clients specifc brands are discussed in the accompa- who have co-occurring mental health and nying text, the name of the medication is substance use disorders. It is not intended as a bolded to assist the reader in fnding the complete guide to client education. This positive haloperidol Haldol, Haldol Decanoate response may include thoughts that are more rational, decreased psychosis1, paranoia and loxapine Loxitane delusions, behavior that is more appropriate, and mesoridazine Serentil the ability to have relationships and work. The newest thiothixene Navane antipsychotic medications—Risperdal, Saphris, Fanapt, Zyprexa, Seroquel, Geodon, and Abilify— trifuoperazine Stelazine show positive effects across a range of disorders. Novel or atypical antipsychotics These medications stabilize mood and are also used to treat bipolar disorder. They are being added to aripiprazole Abilify, Abilify Discmelt antidepressants to treat severe depressions. The physician will specify the exact amount of medication and when it should be taken. Many medications are taken once a day, some at bedtime Antipsychotics (neuroleptics) are most frequently to take advantage of the drowsiness side effect of used for persons who experience psychotic symp- some antipsychotic medications. Several medica- toms as a result of having some form of schizo- tions are taken in pill form or liquid form. Psychotic symptoms may include being out of touch with reality, “hearing voices,” and having false perceptions (e. Antipsychotic medications can be recognize reality, and relationships to others to such a effective in either minimizing or stopping these degree that it interferes with that person’s ability to symptoms altogether. As a result, they are at high risk 6 also important that people talk to their doctor so for infections due to a compromised immune they know about potential side effects and steps system, and this could be fatal. To maintain Novel or atypical antipsychotics are different from safety, white blood cell counts must be checked traditional antipsychotics. These medications are each week for 6 months and every 2 weeks there- effective in treatment-resistant schizophrenia but after. The results must be sent to the person’s may also be used with severe depression or other pharmacy before he or she can pick up the next psychiatric illness. Both are strong and predictable antipsy- dyskinesia2 or neuroleptic malignant syndrome3. Risperidone may cause involuntary The most common mild side effects are either movements, tremors, muscular rigidity, and sedation4 or agitation, especially when starting the immobility without paralysis, and at higher doses medications. Because 9 microencapsulated medication that releases into diabetes is associated with obesity, it is unclear the body at a constant level. An injection is usually whether the diabetes is actually caused by certain given every 2 weeks. In some prison settings, there have been Clozapine can very rarely cause serious abnormali- reports of “abuse” of both quetiapine and olan- ties or irregularities in the blood cells (blood 7 zapine, by prisoners feigning psychotic symptoms dyscrasias ). Ziprasidone involuntary motor movements of the trunk and limbs; occurring especially as a side effect of prolonged use of has also been linked to a serious heart condition antipsychotic medications. This heart condition can 3 neuroleptic malignant syndrome: A very rare but life- lead to dysrhythmia (an irregular heart rhythm) threatening neurological disorder most often caused by a which needs to be treated quickly to prevent reaction to antipsychotic/neuroleptic medications. Typically developing within the frst 2 weeks of treatment; but can serious complications. The syndrome can also occur in people condition is low, but should be looked at by the taking antiparkinsonian medications if discontinued abruptly. A doctor should monitor blood work 5 lipids: Any of various substances including fats, waxes, and in patients that may be more likely to have a heart phosphatides that with proteins and carbohydrates make up condition. A doctor or pharmacist should review the principal structural components of living cells. Paliperidone long- • Temperature above normal acting injections are also available for patients that are stable on paliperidone. This long acting Other injection provides an entire month’s worth of • Blurred vision medication in a single shot and can be useful for • Changes in sexual functioning patients that don’t always remember to take their • Constipation medications. Patients should be told that the • Diminished enthusiasm paliperidone metal capsule will pass with their • Dizziness normal bowel function; this should not be a cause • Drowsiness for alarm. Iloperidone is given twice a day and has a similar action to paliperidone and risperidone. It’s an orally disinte- grating tablet that the patient places on the tongue • Nasal congestion and the tablet will dissolve. In general, the newer antipsychotics, when taken in proper dosage, have • Slurred speech fewer clinical side effects and a broader treatment • Upset stomach response than traditional antipsychotics. Anticholinergic antiparkinsonian • Involuntary movements of the tongue or mouth medications like benztropine or trihexyphenidyl • Jerky, purposeless movements of legs, arms or may be prescribed to control movement diffculties entire body associated with the use of antipsychotic • More often seen in women medications. An • Excessive thirst and hunger overdose is always considered an emergency and • Fatigue treatment should be sought immediately. There are not much data regarding the abuse of traditional antipsychotics currently. Neuroleptic Malignant Syndrome (very rare) One novel antipsychotic that has had reports of • Blood pressure up and down abuse is quetiapine (Seroquel). Physical dependence from For women of childbearing age who may be or continued use of these medications across the class think they may be pregnant, the physician should is rare. Withdrawal reactions such as involuntary discuss the safety of this medication before movements that can last two to four weeks after starting, continuing, or discontinuing medication prolonged use of antipsychotics have been treatment. In order to manage these withdrawal role in encouraging this discussion by suggesting reactions, a slow tapering off of the antipsychotics their clients talk with the prescribing physician. Medications such as benztropine, diphenhydr- Generally, the use of antipsychotic medications amine and trihexyphenidyl can be used during this should be avoided in the frst trimester unless the taper period to lessen the movement’s frequency mother poses a danger to herself, to others, or to and severity. Survey research has Antiparkinsonian (anticholinergic) medications are found that many abusers of antiparkinsonians used used to control the side effects associated with these medications “to get high, to increase plea- antipsychotic medications. They are called antipar- sure, to decrease depression, to increase energy and kinsonian because the neurological side effects of to relax” (Buhrich et al. The survey antipsychotic medications are similar to the also found that the misuse of other drugs accompa- symptoms of Parkinson’s disease (i. The antiparkinsonian medications mental health and substance use disorders, listed in this section are only those used in the providers and consumers need to be aware of and management of the side effects of antipsychotic openly communicate about the abuse potential of medications.
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The mode of transmission is thought to be through inhalation order propranolol 80mg overnight delivery lower blood pressure quickly naturally, ingestion generic propranolol 40 mg without a prescription heart attack kidz bop, or inoculation via the respiratory or gastrointestinal tract buy propranolol now blood pressure chart low bp. Symptoms include fever purchase line propranolol arrhythmia vs dysrhythmia, night sweats, weight loss, fatigue, diarrhea, and abdominal pain. Other focal physical findings or laboratory abnormalities may occur with localized disease. Localized syndromes include cervical or mesenteric lymphadenitis, pneumonitis, pericarditis, osteomyelitis, skin or soft-tissue abscesses, genital ulcers, or central nervous system infection. Other ancillary studies provide supportive diagnostic information, including acid-fast bacilli smear and culture of stool or tissue biopsy material, radiographic imaging, or other studies aimed at isolating organisms from focal infection sites. Available information does not support specific recommendations regarding avoidance of exposure. Azithromycin and clarithromycin also each confer protection against respiratory bacterial infections. Patients will need continuous antimycobacterial treatment unless they achieve immune reconstitution via antiretroviral drugs. Improvement in fever and a decline in quantity of mycobacteria in blood or tissue can be expected within 2 to 4 weeks after initiation of appropriate therapy; clinical response may be delayed, however, in those with more extensive disease or advanced immunosuppression. Adverse effects with clarithromycin and azithromycin include nausea, vomiting, abdominal pain, abnormal taste, and elevations in liver transaminase levels or hypersensitivity reactions. Managing Treatment Failure Treatment failure is defined by the absence of a clinical response and the persistence of mycobacteremia after 4 to 8 weeks of treatment. The regimen should consist of at least two new drugs not used previously, to which the isolate is susceptible. Two studies, each with slightly more than 100 women with first-trimester exposure to clarithromycin, did not demonstrate an increase in or specific pattern of defects, although an increased risk of spontaneous abortion was noted in one study. Diagnostic considerations and indications for treatment of pregnant women are the same as for women who are not pregnant. Pregnant women whose disease fails to respond to a primary regimen should be managed in consultation with infectious disease and obstetrical specialists. Microbiology and Minimum Inhibitory Concentration Testing for Mycobacterium avium Complex Prophylaxis. A prospective, randomized trial examining the efficacy and safety of clarithromycin in combination with ethambutol, rifabutin, or both for the treatment of disseminated Mycobacterium avium complex disease in persons with acquired immunodeficiency syndrome. Early manifestations of disseminated Mycobacterium avium complex disease: a prospective evaluation. Incidence of Mycobacterium avium-intracellulare complex bacteremia in human immunodeficiency virus-positive patients. Incidence and natural history of Mycobacterium avium- complex infections in patients with advanced human immunodeficiency virus disease treated with zidovudine. Disseminated Mycobacterium avium-intracellulare infection in acquired immunodeficiency syndrome mimicking Whipple’s disease. Mycobacterium avium complex infection presenting as endobronchial lesions in immunosuppressed patients. Mycobacterial lymphadenitis associated with the initiation of combination antiretroviral therapy. Mycobacterial lymphadenitis after initiation of highly active antiretroviral therapy. Prophylaxis against disseminated Mycobacterium avium complex with weekly azithromycin, daily rifabutin, or both. A randomized trial of clarithromycin as prophylaxis against disseminated Mycobacterium avium complex infection in patients with advanced acquired immunodeficiency syndrome. Discontinuing or withholding primary prophylaxis against Mycobacterium avium in patients on successful antiretroviral combination therapy. Comparison of combination therapy regimens for treatment of human immunodeficiency virus-infected patients with disseminated bacteremia due to Mycobacterium avium. A randomized, placebo-controlled study of rifabutin added to a regimen of clarithromycin and ethambutol for treatment of disseminated infection with Mycobacterium avium complex. A randomized evaluation of ethambutol for prevention of relapse and drug resistance during treatment of Mycobacterium avium complex bacteremia with clarithromycin-based combination therapy. A randomized, double-blind trial comparing azithromycin and clarithromycin in the treatment of disseminated Mycobacterium avium infection in patients with human immunodeficiency virus. Uveitis and pseudojaundice during a regimen of clarithromycin, rifabutin, and ethambutol. Tolerance and pharmacokinetic interactions of rifabutin and clarithromycin in human immunodeficiency virus-infected volunteers. Paper presented at: national Jewish Center for Immunology and Respiratory Medicine. Recommendations on prophylaxis and therapy for disseminated Mycobacterium avium complex disease in patients infected with the human immunodeficiency virus. In vitro activity of new fluoroquinolones and linezolid against non- tuberculous mycobacteria. Postmarketing surveillance of medications and pregnancy outcomes: clarithromycin and birth malformations. Tachypnea and decreased arterial oxygen saturation indicate moderate-to-severe pneumonia and clinicians should strongly consider hospitalizing such patients. Patients with bacterial pneumonia typically have signs of focal consolidation, such as egophony, and/ or pleural effusion on lung examination. Individuals with bacterial pneumonia characteristically exhibit unilateral, focal, segmental, or lobar consolidation on chest radiograph. The frequency of these typical radiographic findings, however, may depend on the underlying bacterial pathogen. Disease severity and arterial oxygenation should be assessed in all patients with pneumonia. Noninvasive measurement of arterial oxygen saturation via pulse oximetry is an appropriate screening test. Arterial blood gas analysis is indicated for those with evidence of hypoxemia suggested by noninvasive assessment and for patients who have tachypnea and/or respiratory distress. If previous radiographs are available, they should be reviewed to assess for presence of new findings. Gram stain and culture of expectorated sputum should be performed only if a good-quality specimen can be obtained and quality performance measures can be met for collection, transport, and processing of samples. Correlation of sputum culture with Gram stain can help in interpretation of sputum culture data. Bronchoscopy with bronchoalveolar lavage should be considered, especially if the differential diagnosis is broad and includes pathogens such as Pneumocystis jirovecii. Diagnostic thoracentesis should be considered in all patients with pleural effusion, especially if concern exists for accompanying empyema, and therapeutic thoracentesis should be performed to relieve respiratory distress secondary to a moderate-to-large-sized pleural effusion. Modifiable factors associated with an increased risk of bacterial pneumonia include smoking cigarettes and using injection drugs and alcohol. Antibiotic therapy should be administered promptly, however, without waiting for the results of diagnostic testing. Preferred beta-lactams are high-dose amoxicillin or amoxicillin-clavulanate; alternatives are cefpodoxime or cefuroxime.
In general all chemical disinfectants are more effective for microbial inactivation purchase propranolol 40 mg blood pressure how to read, requiring reduced dosage discount propranolol 80 mg with visa arrhythmia with pacemaker, as temperature increases buy propranolol in united states online arteria coronaria dextra. The pH of the water discount propranolol express blood pressure medication starting with a, in the case of chlorination, has a significant effect on its effectiveness particularly requiring increases in the dosage rate above a value of 7. Ozone disinfection is not affected by pH in the common treated water range of 6-9. Rather than list all possible combinations of disinfectants, the following summarises areas that are likely to be of practical significance. Chlorine dioxide also shows a synergistic effect when combined with other disinfectants such as ozone, chlorine, and chloramines. Combination of disinfectants is known to lead to greater inactivation when the disinfectants are added in series rather than individually. Combination of disinfectants would need to take into account interactions between them. There are also benefits from two or more disinfectants in dealing with a range of different types of pathogen of different sensitivities to disinfectants e. However, it is unlikely that sufficiently large ozone residual would reach a final chlorination process, for such chlorate formation to be an issue. Chlorine also reacts with chlorine dioxide to produce chlorate, but it unlikely that these oxidants would be used in such a way as to allow this interaction to occur. Conversely there may be benefits to using chlorinated water to control biological nuisances. The concentrations of these organochlorine by-products are a function of the nature and concentration of oxidisable organic material in the water, the pH of the water, the water temperature, the free chlorine concentration, it’s contact time with the organic material but are not related to the type of chlorine source used. However, there are also inorganic by-products, particularly chlorate and bromate, which can result from the increased use of hypochlorite rather than chlorine gas, as the dosed chlorine chemical and its impact is greater with increasing storage time of the hypochlorite solution. The by-product issues of concern with the main disinfection processes are summarised in Table 3. Where chlorine is obtained from hypochlorite, chlorate and bromate formation can be an issue depending on bromide content of salt used in manufacture and subsequent conditions of storage of hypochlorite. Chlorine dioxide Dosage rates in the future are likely to be limited by consideration of inorganic by products (chlorate and chlorite) in accordance with current international practice. Surface water sources are more susceptible to organochlorine by-product formation than groundwaters because they receive organic matter in runoff from lake and river catchments. This organic matter comprises mostly humic substances from decaying vegetation, much of which can be in dissolved form as well as in colloid form. The concentration of this organic matter in surface water catchments can vary quickly after severe rainfall events or more slowly on a seasonal basis. The greater the portion which makes its way through the treatment process the greater the potential for the production of disinfection by-products. Following application of chlorine as part of the treatment process, organochlorine by-products can continue to form within downstream treated water storage and distribution systems depending on the length of retention times in storage tanks and pipelines and the strength of the disinfectant dose required to maintain chlorine residual in the peripheral areas of a distribution system. Journal Of Environmental Science and Health Part A Toxic/Hazardous Subst ances and Environmental Engineering 2009 Mar;44(4):336-9. In addition to its use as a primary disinfectant post treatment, the residual level which remains in the distribution systems ensures that the microbiological compliance can be quality assured to the consumer tap as well as safeguarding against recontamination in the distribution system. Chlorination is a relatively simple and cost effective process which does not require extensive technical expertise and which is capable of dealing with supply systems of varying size by altering dosing systems or storage for chemical contact accordingly. In Ireland, chlorination has historically been achieved using systems involving the storage and dosage of chlorine gas. Some of these gas installations remain in active use and will require ongoing guidance on their use for water disinfection and for management of associated health and safety risks. However, due to the toxic nature of chlorine gas, these installations have serious health and safety risks, which have to be managed. The ongoing development and availability of other chlorination technologies such as: liquid sodium hypochlorite storage and dosage systems; advances in electrochlorination technology involving the on site batch manufacture of sodium hypochlorite. Most of the newer installations installed in the Irish market now use these liquid hypochlorite technologies as alternatives to gaseous chlorination. Due to the fact that monochloramine is a much weaker disinfectant than chlorine, it’s primary use is as a secondary disinfectant to maintain a residual in distribution networks, due to the difficulty in establishing adequate Ct values for primary disinfection. It is important that the effects and influences of the various post treatment chemical additions on the efficacy of the disinfection systems are understood so that the sequence of their application optimises the disinfection process. The correct pH saturation level of particular treated water is dependent on the residual alkalinity level remaining in the final filtered water. Low alkalinity waters following treatment often have consequent pH saturation levels close to or above a pH of 8. This chemical elevation of pH level causes a calcium carbonate deposit on the inside of lead pipes thereby reducing leaching of lead into drinking water supplies. As a result pH correction for plumbosolvency, using either the addition of lime, sodium carbonate or liquid sodium hydroxide, usually follows chlorination. Fluoridation is achieved by the addition of Hydrofluosilicic Acid (H2SiF6) to water, which releases fluorine in solution. Many existing treatment plants however have limited space and hydraulic head to accommodate the inclusion of static mixers between dosing points and in actuality rely on subsequent contact tanks, pumping plant and treated water storage to ensuring complete mixing. The liquefied gas is delivered to treatment works as cylinders (33 kg and 71 kg net Cl2) and drums (864 kg and 1000 kg net Cl2). For the largest sites it can be delivered in bulk and stored in a specially designed tank. Chlorine is highly toxic and rigorous Health and Safety procedures must be followed, and safety facilities provided, including breathing apparatus and chlorine detectors with alarms. To minimise risk, most of the system for delivering gas to the treatment process is designed to operate under vacuum. The vacuum is provided by an ejector which also serves to provide intense mixing of the gas with the so called “motive water” that delivers the resultant solution of chlorinated water to the dosing point. Good mixing should be provided at the point of dosing, using in-line static mixers if necessary, particularly if the flow divides shortly afterwards. Water Treatment Manual: Disinfection A schematic of a gas chlorination system, using chlorine cylinders, is given in Figure 4. Key Vent R Combined vacuum regulator and pressure relief (duty standby) Vacuum pipe M Solenoid valve Automatic mbar Visual displays of ejector changeover and supply vacuum panel C Duty/standby gas chlorinator Isias Duty/standby injection points R E Duty/standby ejectors D Chlorine gas detector Manifold Flexible coupling Adjoining pipe room E E Standby Duty Chlorinated water Motive water pumps Main process Figure 4. The rate of gas flow, which is indicated by a flowmeter, is controlled by adjusting the area of the orifice. Control of the rate of flow of gas may be varied manually or automatically, so that a constant residual concentration of chlorine is left in a flow of water to form a concentrated chlorine solution. The inlet stream of water passes through a venturi tube or orifice at the heart of the injector causing the water velocity to increase and its pressure to fall, so that at that moment it can suck in the chlorine gas with which it mixes. Downstream of the constriction the pipe diverges, so that the original pressure is nearly fully regained.