Abstract: An improved safety IV placement device includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after placement of the IV cannula and removal of the needle from within the cannula. An internal spring, which engages the sheath, expands to move the sheath to cover the needle point prior to placement of the IV cannula and after the needle is removed from the indwelling cannula. The spring is a non-uniform helical spring having multiple 360 turns each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe for dental applications which further includes first finger grip, preferably a thumb ring, on the end of the plunger, forward finger holders and a lock mechanism, which includes extending fingers for grasping the top of the reciprocal sliding sheath. The syringe assembly also includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body. The fingers, preferably biased by a living hinge hold back the locking ring while the dentist administers anesthesia through the syringe. An internal spring, which engages the syringe body and the sheath, expands to move the sheath to cover the needle point. The spring is a non-uniform helical spring having multiple 360° turns with each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe for dental applications which further includes first finger grip, preferably a thumb ring, on the end of the plunger, forward finger holders and a lock mechanism, which includes extending fingers for grasping the top of the reciprocal sliding sheath. The syringe assembly also includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body. The fingers, preferably biased by a living hinge hold back the locking ring while the dentist administers anesthesia through the syringe. An internal spring, which engages the syringe body and the sheath, expands to move the sheath to cover the needle point. The spring is a non-uniform helical spring having multiple 360° turns with each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body, a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body, and a spring engaging the syringe body and the sheath and expandable to move the sheath to cover the needle point, where the spring is a non-uniform helical spring having multiple 360° turns each turn uniformly spaced from adjacent turns, each 360° turn comprising first and second alternating angled portions, the first of the alternating angled portions being at a first angle to a plane perpendicular to an axis through the center of the helical spring and the second angled portions being at a second lesser angle to the plane perpendicular to the axis.

Abstract: An improved safety IV placement device includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body and a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after placement of the IV cannula and removal of the needle from within the cannula. An internal spring, which engages the sheath, expands to move the sheath to cover the needle point prior to placement of the IV cannula and after the needle is removed from the indwelling cannula. The spring is a non-uniform helical spring having multiple 360 turns each turn uniformly spaced from adjacent turns.

Abstract: An improved safety hypodermic syringe includes a reciprocal tubular needle sheath disposed on the exterior of the syringe body, a latch mechanism engaging the syringe body and the sheath to latch the sheath in a needle-covering position after delivering contents from the syringe body, and a spring engaging the syringe body and the sheath and expandable to move the sheath to cover the needle point, where the spring is a non-uniform helical spring having multiple 360° turns each turn uniformly spaced from adjacent turns, each 360° turn comprising first and second alternating angled portions, the first of the alternating angled portions being at a first angle to a plane perpendicular to an axis through the center of the helical spring and the second angled portions being at a second lesser angle to the plane perpendicular to the axis.

Abstract: This invention relates to reciprocable sheaths for hypodermic syringes that have latches to hold the sheaths over the needle of the syringes. A spring is employed to normally move the sheath over the needle and the expansion of the spring is limited to 90.degree. of the free expansion dimension to positively move the sheaths and latches to the fully protected position. Volume numbers and graduations are placed on the exterior of the syringe plumger for greater clarity of reading.

Abstract: This specification discloses a lock for a latch on a hypodermic syringe which has a reciprocating sheath that is normally latched to cover the needle to protect persons handling the syringe. The latch is operated to withdraw the sheath to expose the needle for use. The latch shell 22 is moved longitudinally to actuate latch fingers 26. After use it is desirable to lock the latch to prevent reuse of the syringe. A user manually rotates the latch shell 20 to lock the latch in the position where the sheath is over the needle. Rotary motion causes the lugs 26 to ride up the ramps 28 and then drop into the recesses 29. Thereafter, there can be no rotation and no reciprocation of the latch. The lugs prevent rotary motion as well as reciprocating motion of the latch shell 22.

Abstract: A tubular hypodermic needle syringe has a tubular sheath that slides over the exterior of the syringe to cover the needle. The sheath is locked over the needle by a latch that engages the syringe and the sheath. The latch is held in its locking engagement by a sliding collar that normally engages the latch to lock the latch but which is manually slidable to disengage the latch so that the sheath can be manually moved to expose the needle. A spring urges the collar to a latch engaging position to automatically lock the sheath over the needle.

Abstract: A pair of probes is disposed in a pipe supplying water that has been treated to reduce inorganic solids to a selected level. A supply voltage is impressed across the probes to create a signal voltage that is a measurement of the ionization potential in the water between the probes. A dip switch and resistors of progressively different values are connected across the voltage source, and one switch of the dip switch is manually closed that represents the upper limit or range of desired dissolved solids. A signal voltage is created by the dip switch resistor, and the probe voltage and the dip switch voltage are supplied to an amplifier. If the difference on the two voltages is high, then a flip-flop energizes a red light indicating excessive solids; and if the difference is small, then the flip-flop energizes a green light showing an acceptable level of solids.