What is Full Vacuum Pressure?
Full vacuum pressure (and, indeed, all vacuum pressures) more-or-less refers to the absence of anything; anything, in this case, being any type of matter or substance (including molecules of oxygen and other gases). Ducts aspire to reach this level of full vacuum pressure because, when vacuums exist, air immediately rushes into fill the empty space, fueling movement. This is, in essence, how ducts and ducting, on the whole, works. However, according to www.framl.nl, “in practice achieving complete emptiness is impossible. Even the outer space is not empty of matter.” So, if full vacuum pressure does not actually exist: how do duct hoses actually work? Firstly full vacuum in an industrial hose is pulling negative pressure or sucking in.
The use of a vacuum that can be as low (or high?) as 99% of the outside pressure. Say 29.5 "Hg or 1 Bar. in fact in vacuum terminology this is considered as "Medium Vacuum". Generally for most flexible industrial ducting 29Hg is in fact the maximum negative pressure that a hose can withstand. Hoses above 4-inch in diameter are generally not capable of handling this negative pressure. In addition flex ducts made from less sturdy materials like fabric are almost always incapable of pulling a full vacuum.
Well, the answer is that they do not actually require full vacuum in order to be effective. Most ducts will typically generate a vacuum of 99%, which for most intents and purposes is just as good as true full vacuum pressure (although, technically, most physicists would classify 99% emptiness as “only” a medium vacuum). What’s more, the smaller the inside diameter of the ducting, the easier it will be to generate a more complete vacuum. 1” vacuum hose and 4” vacuum hose are among the most popular types of heavy duty hose because of the ease of generating a comprehensive vacuum throughout the length and span of the hose.
In understanding vacuums and how they relate to ducts, it is important to understand how vacuums are measured. In the imperial system, we typically use pounds per square inch (psi) to connote the pressure (or lack thereof) caused by vacuums. If a 1” vacuum hose (or a 4” vacuum hose, et al.) features a psi of 0, that means that the ducting in question is at 0% vacuum pressure (otherwise known as “standard atmosphere”). -14.7 psi, on the other hand, is absolute full vacuum pressure, meaning that the duct hose is as empty as can ever be possible. As we established earlier however, in practice, this is unobtainable and, indeed, unnecessary when it comes to residential or commercial ducting applications.
Because heavy-duty hoses rely on having nearly complete vacuums to generate airflow and safely transport fumes and other chemicals, it is imperative that leaks and cracks in the piping be avoided at all costs. Generally, the airflow of ducts is measured in cubic feet -of air- per minute (cfm). Even small leaks, however, can severely impact a pipe’s performance and its cfm capacity. Per www.fram.nl, “a hole of 4.5 mm diameter (less than 3/16") will nearly halve the vacuum performance of a 20 m3/h (12 cubic feet per minute) vacuum pump.” As a result of this, increasing numbers of home and OEM manufacturers are relying on reinforced hose products to shift and move their valuable (and sometimes hazardous) gasses and fumes from place to place. By specifically incorporating heavy duty hoses into their ducting applications, consumers are taking an important step in abating the headaches (literal and figurative) caused by leaky duct hoses.
Here are a few of our hoses that can handle a full vacuum
PE Flex Plus - Sizes 2 inch ID and under
PE Flex Vaculoop – Sizes 1.25” ID or smaller
Urethane Flex Heavy Duty - Sizes 4”ID and under
Full vacuum pressure is an intriguing and elusive notion, but it is important to at least have a general understanding regarding vacuums themselves, and how they relate to ducting and ducts of all sized. Whether it is 1” vacuum hose, 4” vacuum hose, vacuum pressure influences virtually every aspect of the hosing’s affectivity. With this information in mind, you are better equipped to dealing with and handling the responsibilities and practicalities involved in the flexible ductwork industry.