Some 19th-century or earlier experimental engines used external flames, exposed by valves, for ignition, but this becomes less attractive with increasing compression.

Some common operational problems are intrusion of air into the drive pipe, blockage of the intake or valves with debris, knocking due to having too little air in the pressure vessel, freezing in winter and bursting of the delivery pipe if output is blocked or pressure not relieved.

Some valves have neither handle nor actuator because they automatically control themselves from inside ; for example, check valves and relief valves may have neither.

Some valves have no external control and do not need a stem as in most check valves.

Some valves are made to be operated in a gradual change between two or more positions.

Some valves are specially designed to regulate varying amounts of flow.

Some valves rated at very high pressures are available.

Some models benefit from variable camshaft timing, and multiple valves per cylinder.

Some of the specimens, such as the Tai Chi Man, demonstrate interventions, and include prosthetics such as artificial hip joints or heart valves.

Some operational problems were reported due to the high viscosity of vegetable oils compared to petroleum diesel fuel, which results in poor atomization of the fuel in the fuel spray and often leads to deposits and coking of the injectors, combustion chamber and valves.

Some bass-baritones were equipped with full-tone rotary valves to F in order for some of the hornline to be able to achieve the desired Bugle Low A, and in the mid-1960s a bass-baritone rotor to E was briefly offered.

Some patients with prosthetic heart valves however need antibiotic prophylaxis for dental surgery because bacteremia might lead to endocarditis ( infection causing inflammation of the interior lining of the heart ).

Some types of irrigation sprinklers and drip irrigation emitters have small check valves built into them to keep the lines from draining when the system is shut off.

Some of the early CVCC engines had a problem with the auxiliary valves retaining collars vibrating loose.

Some airless pumps have a diaphragm instead of a piston, but both types have inlet and outlet valves.

Some GCs also include valves which can change the route of sample and carrier flow.

Some ball valves are equipped with an actuator that may be pneumatically or motor operated.

Some governments require the use of two chemigation valves installed in series if hazardous chemicals are to be injected.

Some of the less directly visible differences were poorly shaped ports in the earlier versions, a slow burning combustion chamber with heavily shrouded valves, less aggressive camshaft profiles, ports of a small cross sectional area, a very restrictive intake manifold with long runners joined to a small displacement plenum and other changes.

Some blowoff valves are sold with a trumpet-shaped exit that intentionally amplifies the sound.

Some SOHC multi-valve engines ( such as the Mazda B8-ME ) use a single fork-shaped rocker arm to drive two valves ( generally the exhaust valves ) so that fewer cam lobes will be needed in order to reduce manufacturing costs.

Some 45 frequencies are assigned for use primarily by dominant Class 1, -- A or Class 1, -- B clear-channel stations, designed to operate with adequate power and to provide service -- both groundwave and ( at night ) skywave -- over large areas and at great distances, being protected against interference to the degree necessary to achieve this objective.

Some cases in evidence of the use of roleplaying for analysis may help explain the procedure.

Some of Thurber's curative methods involve strong potions of mixed metaphor, malapropism, and gobbledygook and are recommended for use only in extreme cases.

Some popular designs use the following types of ANOVA:

Some sources mention the use of an abacus called a nepohualtzintzin in ancient Mayan culture.

Some adaptations of the Latin alphabet are augmented with ligatures, such as æ in Old English and Icelandic and Ȣ in Algonquian ; by borrowings from other alphabets, such as the thorn þ in Old English and Icelandic, which came from the Futhark runes ; and by modifying existing letters, such as the eth ð of Old English and Icelandic, which is a modified d. Other alphabets only use a subset of the Latin alphabet, such as Hawaiian, and Italian, which uses the letters j, k, x, y and w only in foreign words.

Some amateur astronomers use home-made radio telescopes, while others use radio telescopes that were originally built for astronomy research but have since been made available for use by amateurs.

Some may suggest that it is probably advisable to use mouthwash at least an hour after brushing with toothpaste when the toothpaste contains sodium lauryl sulfate, since the anionic compounds in the SLS toothpaste can deactivate cationic agents present in the mouthrinse.

Some results in constructive set theory use the axiom of countable choice or the axiom of dependent choice, which do not imply the law of the excluded middle in constructive set theory.

Some abugidas use a special symbol to suppress the inherent vowel so that the consonant alone can be properly represented.

Some modern descendants of this culture often choose to use the term " Ancestral Pueblo " peoples.

Some of the Australians wanted to use Bodyline in retaliation, but Woodfull flatly refused.

Some hard science fiction stories use small ( possibly nano-sized ) paired wormholes dedicated to communication by means of a laser which traverses the wormhole.

( Some newer protocols, such as Kerberos and Active Directory use DNS SRV records to identify services by name, which is much closer to the AppleTalk model.

Some consider such use of the term " incorrect.

Some natural tolerance to habitual use of ayahuasca ( roughly once weekly ) may develop through upregulation of the serotonergic system.

Some reports and scientific studies affirm that ritualized use of ayahuasca may improve mental and physical health.

Some Protestant US military chaplains carry the Roman Rite version of the Anointing of the Sick with them for use if called upon to assist wounded or dying soldiers who are Catholics.

Some Nasheed singers avoid instruments in the background due to the opinion of certain scholars that their use is prohibited.

Some guns were suitable for dual-role anti-aircraft and field ( anti-tank ) use.

Some studies have found decreased life expectancy associated with the use of antipsychotics, and argued that more studies are needed.

Some doubts have been raised about the long-term effectiveness of antipsychotics for schizophrenia, in part because two large international World Health Organization studies found individuals diagnosed with schizophrenia tend to have better long-term outcomes in developing countries ( where there is lower availability and use of antipsychotics and mental health problems are treated with more informal, community-led methods only ) than in developed countries.

Some critics have also analyzed the use of alleged front organizations and conflicted patient " advocacy " groups funded by pharmaceutical companies that seek to set the mental health agenda, including the use of the law to force people to take antipsychotics against their will, often justified by claims about risk of violence.