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PDFtk (short for PDF Toolkit) is a toolkit for manipulating Portable Document Format (PDF) documents. [3] [4] It runs on Linux, Windows and macOS. [5] It comes in three versions: PDFtk Server (open-source command-line tool), PDFtk Free and PDFtk Pro (proprietary paid). [2] It is able to concatenate, shuffle, split and rotate PDF files.
PDF 2.0 defines 256-bit AES encryption as the standard for PDF 2.0 files. The PDF Reference also defines ways that third parties can define their own encryption systems for PDF. PDF files may be digitally signed, to provide secure authentication; complete details on implementing digital signatures in PDF are provided in ISO 32000-2.
A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. [1] This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.
A ball valve is a flow control device which uses a hollow, perforated, and pivoting ball to control fluid flowing through it. It is open when the hole through the middle of the ball is in line with the flow inlet, and closed when it is pivoted 90 degrees by the valve handle, blocking the flow. [1]
Schematic 3 way ball valve: L-shaped ball right, T-shaped left. Valves with three ports serve many different functions. A few of the possibilities are listed here. Three-way ball valves come with T- or L-shaped fluid passageways inside the rotor. The T valve might be used to permit connection of one inlet to either or both outlets or connection ...
Ordinary valves can have many ports and fluid paths. A 2-way valve, for example, has 2 ports; if the valve is open, then the two ports are connected and fluid may flow between the ports; if the valve is closed, then ports are isolated. If the valve is open when the solenoid is not energized, then the valve is termed normally open (N.O.).
The inside of an extremely large butterfly valve Duplex ball valve Three check valves in corrosion-resistant Hastelloy Stainless steel gate valve. Valves can be categorized into the following types, based on their operating mechanism: Ball valve, for on–off control without pressure drop. Ideal for quick shut-off, since a 90° turn completely ...
Globe valve. A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable plug or disc element and a stationary ring seat in a generally spherical body. [1] Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle.