as described above , in the high pressure process for the production of 1233zd , the operating conditions of the reactor are extremely aggressive ( e . g ., 140 ° c . and 400 psig ) and the process employs reactant materials that are highly corrosive under these reaction conditions . the process requires agitation to allow the reaction to proceed . as such , the design of the agitator is critical to ensure an appropriate operating lifetime in the harsh conditions . the present invention is directed to one such reactor and agitator design . ( a ) double mechanical seal with an inert barrier fluid such as fluorolube . ( b ) silicon carbide ceramics ( or the like ) on the rotating faces of the seal . ( c ) silicon carbide ceramics ( or the like ) may also be used on the static faces of seal . ( e ) wetted metal surfaces of the agitator are constructed of an appropriate nickel alloy such as alloy 20 , the hastelloy alloys or the inconel alloys . as shown in fig1 , an agitator according to the present invention includes a double mechanical seal consisting of a ceramic material , e . g ., silicon carbide and equivalents , on the rotating faces , wetted parts that are constructed of an appropriate nickel alloy , and spring - energized o - rings . the agitator may be installed in a top or bottom mount position . as shown in fig2 , a reactor vessel according to the present invention includes an agitator of the style of fig1 , materials of construction of an appropriate nickel , alloy ( either solid or clad ), and may contain an external or internal heating or cooling system . the design may be modified to feed reactants in the liquid or vapor phase and may be fed to the bottom or top of the vessel . corrosion resistant alloys are known and are preferred materials used in the construction of the reactor vessel and agitator of the present invention . some of the commercially available corrosion resistant alloys include the following : nickel 200 is commercially pure ( 99 . 6 %) wrought nickel . it has good mechanical properties and excellent resistance to many corrosive environments . monel ® nickel - copper alloy 400 is a solid solution alloy that may be hardened only by cold working . it has high strength and toughness over a wide temperature range and excellent resistance to many corrosive environments . inconel ® nickel - chromium - iron alloy 600 is a standard engineering material for applications which require resistance to corrosion and heat . the alloy shows resistance to oxidizing conditions at high temperatures or in corrosive solutions . inconel ® nickel chromium alloy 625 is used for its high strength , excellent fabricability ( including joining ), and outstanding corrosion resistance . inco alloy c - 276 is known for its outstanding corrosion resistance in a wide range of severe media . the high nickel and molybdenum contents provide good corrosion resistance in reducing environments while chromium imparts resistance to oxidizing media . incoloy ® alloy 800 is a widely used material of construction for equipment that must have high strength and resist oxidation , carburization , and other harmful effects of high - temperature exposure . the chromium in the alloy imparts resistance to oxidation and corrosion . incoloy ® alloy 825 is a nickel - iron - chromium alloy with additions of molybdenum , copper and titanium . the alloy &# 39 ; s chemical composition is designed to provide exceptional resistance to many corrosive environments . inco alloy 020 is an austenitic nickel - iron - chromium alloy with additions of copper and molybdenum . the nickel content makes inco alloy 020 resistant to chloride - ion stress - corrosion cracking copper and molybdenum give resistance to reducing environments . the molybdenum content also provides good resistance to pitting and crevice corrosion . the chromium gives resistance to oxidizing environments . hastelloy ® is the trademark name for a range of twenty two different highly corrosion - resistant metal alloys loosely grouped by the metallurgical industry under the material term “ superalloys ” or “ high - performance alloys ”. the predominant alloying ingredient is typically the transition metal nickel . an agitator is constructed of alloy 20 wetted parts and a double mechanical seal with fluorolube barrier fluid , silicon carbide on all seal faces , spring - energized teflon o - rings and a ptfe wedge system was operated at conditions ranging from 100 to 400 psig and 90 ° to 145 ° c . in a process to produce hfco - 1233zd from hf and hcc - 240 . the agitator operated successfully for several months . an agitator constructed of alloy 020 wetted parts and a double mechanical seal with fluorolube barrier fluid , silicon carbide on all seal faces , perfluoroelastomer o - rings and a ptfe wedge system was operated at conditions ranging from 100 to 400 psig and 90 ° to 145 ° c . in a process to produce hfco - 1233zd from hf and hcc - 240 . the agitator seal system failed after 3 weeks of operation due to chemical attack of the perfluoroestomer wetted o - rings . an agitator constructed of alloy 020 wetted parts and a double mechanical seal with fluorolube barrier fluid , tungsten carbide on the rotating seal face , perfluoro - elastomer o - rings and a ptfe wedge system was operated at conditions ranging from 100 to 150 psig and 90 ° to 100 ° c . in a process to produce hfco - 1233zd from hf and hcc - 240 . the agitator seal system failed after 2 weeks of operation due to failure of the seal faces . as used herein , the singular forms “ a ”, “ an ” and “ the ” include plural unless the context clearly dictates otherwise . moreover , when an amount , concentration , or other value or parameter is given as either a range , preferred range , or a list of upper preferable values and lower preferable values , this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value , regardless of whether ranges are separately disclosed . where a range of numerical values is recited herein , unless otherwise stated , the range is intended to include the endpoints thereof , and all integers and fractions within the range . it is not intended that the scope of the invention be limited to the specific values recited when defining a range . it should be understood that the foregoing description is only illustrative of the present invention . various alternatives and modifications can be devised by those skilled in the art without departing from the invention . accordingly , the present invention is intended to embrace all such alternatives , modifications and variances that fall within the scope of the appended claims .