[vc_row rtl_reverse=”yes”][vc_column width=”2\/3″][vc_single_image image=”666″ alignment=”center” animation_type=”flash”][vc_column_text]<\/p>\n
A needle valve is a type of valve having a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates.<\/span><\/p>\n [\/vc_column_text] An Instrument Needle Valve uses a tapered pin to gradually open a space for fine control of flow. The flow can be controlled and regulated with the use of a spindle. A needle valve has a relatively small orifice with a long, tapered seat, and a needle-shaped plunger on the end of a screw, which exactly fits the seat.<\/span> [\/vc_column_text][\/vc_column][vc_column width=”1\/3″ text_align=”right”][vc_text_separator title=”\u0627\u0631\u062a\u0628\u0627\u0637 \u0628\u0627 \u0645\u0627” color=”custom” border_width=”10″ css_animation=”bounceIn” css=”.vc_custom_1604345607602{padding-top: 15px !important;padding-bottom: 30px !important;}” accent_color=”#0088cc”][vc_tta_accordion][vc_tta_section i_icon_fontawesome=”fas fa-user-tie” add_icon=”true” title=”\u0645\u062f\u06cc\u0631 \u0628\u0627\u0632\u0631\u06af\u0627\u0646\u06cc” tab_id=”1604332461974-2fd3e027-6ead”][\/vc_tta_section][vc_tta_section i_icon_fontawesome=”fas fa-user-tie” add_icon=”true” title=”\u06a9\u0627\u0631\u0634\u0646\u0627\u0633 \u0641\u0631\u0648\u0634” tab_id=”1604333716792-b0fef2de-2187″][\/vc_tta_section][\/vc_tta_accordion][\/vc_column][\/vc_row][vc_row css=”.vc_custom_1604332277038{padding-bottom: 20px !important;}”][vc_column][vc_single_image image=”663″ img_size=”medium” alignment=”center” onclick=”link_image” lightbox=”yes” animation_type=”flash”][vc_text_separator title=”Uses” color=”custom” border_width=”10″ css_animation=”bounceIn” element=”h3″ css=”.vc_custom_1614506620585{padding-top: 15px !important;padding-bottom: 15px !important;}” accent_color=”#0088cc”][vc_column_text]<\/p>\n Needle valves are usually used in flow metering applications, especially when a constant, calibrated, low flow rate must be maintained for some time, such as the idle fuel flow in a carburetor.<\/span><\/p>\n \u00a0\u00a0 Note that the float valve of a carburetor (controlling the fuel level within the carburetor) is not a needle valve, although it is commonly described as one. It uses a bluntly conical needle, but it seats against a square-edged seat rather than a matching cone. The intention here is to obtain a well-defined seat between two narrow mating surfaces, giving firm shutoff of the flow from only a light float pressure.<\/span><\/p>\n Since flow rates are low and many turns of the valve stem are required to completely open or close, needle valves are not used for simple shutoff applications.<\/span><\/p>\n Since the orifice is small and the force advantage of the fine-threaded stem is high, needle valves are usually easy to shut off completely, with merely “finger tight” pressure. The spindle and\/or seat of a needle valve, especially one made from brass, are easily damaged by excessive turning force when shutting off the flow.<\/span><\/p>\n [\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n","protected":false},"excerpt":{"rendered":" [vc_row rtl_reverse=”yes”][vc_column width=”2\/3″][vc_single_image image=”666″ alignment=”center” animation_type=”flash”][vc_column_text] A needle valve is a type of valve having a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates. [\/vc_column_text][vc_column_text] An Instrument Needle Valve uses a tapered pin to gradually open a space for […]<\/p>\n","protected":false},"author":1,"featured_media":663,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"cybocfi_hide_featured_image":"yes","footnotes":""},"categories":[10,11],"tags":[],"class_list":["post-665","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-products","category-valve"],"featured_image_src":{"landsacpe":["https:\/\/ramanpsr.com\/psr-co\/uploads\/2021\/02\/needlevalve1-1140x445.jpg",1140,445,true],"list":["https:\/\/ramanpsr.com\/psr-co\/uploads\/2021\/02\/needlevalve1-463x348.jpg",463,348,true],"medium":["https:\/\/ramanpsr.com\/psr-co\/uploads\/2021\/02\/needlevalve1-300x264.jpg",300,264,true],"full":["https:\/\/ramanpsr.com\/psr-co\/uploads\/2021\/02\/needlevalve1.jpg",1224,1078,false]},"yoast_head":"\nConstruction and operation<\/h2><\/div>
\nAs the screw is turned and the plunger retracted, flow between the seat and the plunger is possible; however, until the plunger is completely retracted the fluid flow is significantly impeded. Since it takes many turns of the fine-threaded screw to retract the plunger, precise regulation of the flow rate is possible.<\/span>
\nThe virtue of the needle valve is from the vernier effect of the ratio between the needle’s length and its diameter, or the difference in diameter between needle and seat. A long travel axially (the control input) makes for a very small and precise change radially (affecting the resultant flow).<\/span>
\nNeedle valves may also be used in vacuum systems, when a precise control of gas flow is required, at low pressure,[1] such as when filling gas-filled vacuum tubes, gas lasers and similar devices.<\/span><\/p>\n